A diode end-pumped passively mode-locked Nd∶YVO4 picosecond laser with home made semiconductor saturable absorber mirror (SESAM) is presented. By choosing a low-transmission output coupler and extending the cavity length, the Q-switching mode-locked pulses are suppressed and the proportion of direct current is decreased in V shaped resonator. When the cavity length is increased from 0.66 m to 1.27 m and 1.86 m, the proportion of direct current is decreased from 52% to 13.6% and 0.3%. At last, a stable continuous mode-locked pulses are attained and the pulse repetition rate is 80 MHz. The spectral width is measured to be 0.15 nm. Considering the thermal effect of the crystal, a four-mirror Z-cavity is designed using the matrix method. Average output power of 1 W at a pulse repetition rate of 150 MHz is obtained. The benefit and disadvantage of the V-shaped cavity and the four-mirror Z-cavity are compared and analyzed.