[Abstract]:In English writing teaching practice, two kinds of writing training forms are often adopted. The relationship between the two different task conditions and writing achievement and writing strategy is discussed in this paper. The effective solution of this problem is of great significance to further deepen the study of writing strategies and English writing teaching practice. This study makes a quantitative and qualitative study on the achievement of English writing, the use of writing strategies and the interrelationship between them under different task conditions. Combing domestic and foreign writing strategies and establishing three sub-categories of writing strategies: metacognitive strategies, cognitive strategies and social affective strategies, cognitive strategies are subdivided into planning strategies, modifying strategies and vocabulary use strategies. Based on this, the questionnaire is designed. A total of 154 non-English major students in the freshman year of China University of Mining and Technology were assigned writing tasks with different task conditions. Then the strategies used in the writing process were investigated by questionnaire and the corresponding data were collected. The effects of different task conditions on writing achievement, different task conditions and different English proficiency on the use of writing strategies were analyzed by paired sample t-test and independent sample t-test. The structural equation model of English writing under different task conditions is constructed to reveal the relationship among task conditions, writing achievement and the use of writing strategies. The results show that: first, different task conditions have a significant impact on learners' writing performance, and learners' performance in non-time limited writing is significantly higher than that in pre-curricular writing; Secondly, different task conditions and different English proficiency can lead to significant differences in the use of writing strategies. Planning strategies are more used in class time limited writing than modified strategies in non-time limited writing. There is no significant difference in the use of other strategies. In addition, under the same writing conditions, there are significant differences in the use of the three cognitive strategies among the learners of different proficiency groups, and the use of cognitive strategies is more frequent among the high-level learners. There is no significant difference in the use of metacognitive strategies and social affective strategies. Finally, by constructing the structural equation model of writing under different task conditions, this paper reveals the interrelation and influence among task conditions, writing achievement and writing strategy use. The results showed that: (a) under the condition of time-limited writing, cognitive strategies and metacognitive strategies were significantly positively correlated with writing scores, while the influence of social affective strategies on writing scores was not significant; B) under the condition of non-limited writing, cognitive strategies were positively correlated with writing scores, while metacognitive strategies and social affective strategies were not significantly correlated with writing scores. The present study provides the following enlightenment to English teaching: (1) Teachers can adopt the combination of time limited writing in class and non-limited writing in class to conduct writing training, according to the specific requirements of writing teaching and the different emphasis on the training of writing strategies; (2) Teachers should adopt appropriate teaching methods to promote the rational use of writing strategies and teach them according to learners' English proficiency and individual differences.