We demonstrated the active shaping for a solid-state Nd:YVO4 amplifier with a high average gain of 39.2 dB. The average output power was 8.3 W with respect to the input power of 1 mW. A range of common and useful pulse shapes was generated at the final output. In addition, a very flat square pulse was produced with a root-mean-square less than 3% in amplitude. A numerical method was proposed to realize active shaping without an experimental test for the Nd:YVO4 amplifier, showing great potential for the design of lasers with both high peak power (>100 kW) and a desired pulse shape.