The characteristics of diode-side-pumped linear resonator were discussed in the stable condition of the laser resonator. Based on the analyses of the resonator, a simple linear resonator was designed, which was favorable for the modelocking with good laser mode and without astigmatism. In the experiment, the homemade semiconductor saturable absorber mirror was employed for passive mode-locking. Stable continuous-wave mode locking was achieved at 100 MHz repetition rate with 10 ps of pulse duration and the average output power was 2 W. Furthermore, the effects of the parameters of SESAM for the mode-locking were discussed.