  Secure key rate of decoy-state quantum key distribution protocols has been
improved with biased basis choice, however, the security standards and
parameters of current protocols are different. As a result, we cannot give an
accurate key rate comparison between different kinds of protocols. Taking the
schemes based on different formula of secure key rate as examples, we give a
fair comparison between typical protocols under universal composable security
standard. Through analyzing the relationship of security parameters in
post-processing stage and final secure key, we achieve the unified
quantification between protocols based on Gottesman-Lo-Lutkenhaus-Preskill
formula and the ones under universal composable security. Based on the above
research, the impact of different sending length and secure parameters on
secure key rate is investigated, meanwhile, we give the dependent relationship
between secure key rate and sending length under different secure parameters.
Besides, we analyze the importance and conditions of fair comparison. For the
first time we give a fair comparison between the protocols based on GLLP
formula and smooth entropy, and taking Raymond protocol and Toshiba protocol as
examples, we analyze the way for improving secure key rate in the light
intensity choice and the single bit error rate estimation method.
