Quasi-isentropic compression technique is very useful for new material, shock wave physics, and earth physics. With shaping pulse laser, the quasi-isentropic compression technique is provided. For the designed experimental condition, the high energy density of shaping lasers can be used to generate shockless loading on the solid material to reach a high compression rate state with low temperature, which cannot be obtained with shock compression and isentropic compression technique. Then a new way to study the material can be provided. In this paper, the isentropic compression experiment with laser direct-drive illumination based on Shen Guang-III prototype laser facility is conducted. The theoretical model, target designing, experimental results, key technique, experimental characteristics and experimental data are analyzed in detail. The compression pressure above 400 GPa on the loading surface is obtained with experimental data and processing program, which is the highest pressure achieved to date. After comparing the apparent particle velocity with the true particle velocity, the dynamic correction curve can be obtained to achieve the real particle velocity, which is more accurate. The improving direction is provided, which will provide the important information. The experimental data and design will give the valuable reference for the study in this field.