Abstract: There exists the gradient distribution of radial electron velocity due to space charge effect of intense electron beam, and this influences significantly the cooling efficiency. By analysis of the space charge field of intense electron beam in the cooling section of electron cooler system, the variations of electron beam velocity are given. In addition, electron gets the transversal drift velocity and meanwhile causes an additional temperature rise in this crossing field produced by space charge field and longitudinal solenoid field. Using the typical parameters of HIRFLCSR ecooler system, some important conclusions have been drawn.