Recently,semiconductor saturable absorbers mirror (SESAM) have become the important components in the compact mode-locking solid-state lasers.We designed a side-pumped folded cavity Nd:YAG solid laser mode-locking with SESAM and get the highest average output power about 9.45 W.The single pulse has about 141 nJ energy and 71 MHz repetitionrate.With exactly measurement about the thermal focal length,special cavity can be designed to control the mode radius.Although the laser was pumped by high power laser diode (LD) (over hundreds watts),but it still has very well beam quality (nearly the diffraction-limited beam).From this work ,it get closer towards the high power mode-locked solid laser.