To meet three-step 3ω temporally shaped pulse (the pulse-width ratio of three steps is 1.5 ns:1 ns:0.5 ns and the amplitude ratio is 1:4:16) required by phgsics experiment,preliminary laser-pulse-shaping experiment is performed on technical integration line (TIL). Firstly,laser energy and pulse shape of the injection laser system (pre-amplification system) are primarily predicted to tune out systematic differences among the eight beams by laser performance simulation model according to the shot mission and previous data.Secondly,several laser shots at different laser power are done to further modify the pulse shape:1ω energy and 1ω pulse are corrected by the experimental frequency conversion efficiency for every beam,The injection laser energy by fitting experimental input and output energy data,and the injection pulse shape by gain-fluence curve based on the above corrected 1ω pulse and 1ω energy. Finally,all the injection pulses are compromised again for the final pulse shaping. The experimental 8-beam three-step pulses of 3ω at target are comparatively consistent with the requirement. For 3ω-3 ns-0.5 kJ (single-beam) pulse,the three-step beam-to-beam instantaneous root mean square (rms) power imbalance are about 30%,10% and 5%,respectively.