  After the previous work on gravitational frequency shift, light deflection
(arXiv:1003.5296) and perihelion advance (arXiv:0812.2332), we calculate
carefully the fourth gravity test, i.e. radar echo delay in a central gravity
field surrounded by static free quintessence matter, in this paper. Through the
Lagrangian method, we find the influence of the quintessence matter on the time
delay of null particle is presence by means of an additional integral term.
When the quintessence field vanishes, it reduces to the usual Schwarzschild
case naturally. Meanwhile, we also use the data of the Viking lander from the
Mars and Cassini spacecraft to Saturn to constrain the quintessence field. For
the Viking case, the field parameter $\alpha$ is under the order of $10^{-9}$.
However, $\alpha$ is under $10^{-18}$ for the Cassini case.
