LS nylon 12 is used to design and produce a low-bearing capacity and thin-wall water retaining plate structure for the launch vehicle body.The mechanical, thermal, fracture microstructure and SLS processing parameters of SLS nylon 12 and its carbon fiber reinforced materials are emphatically studied. Studies have shown that using nylon 12 powder with the brand X1556 as the material of the water retaining plates,the unnotched impact strength of the material is 81.2 kJ/m² the elongation at break is 26.9%, and the temperature difference of the sintering window is 26.0℃. The material has good impact strength, fracture toughness and a wide range of sintering window temperatures. In addition, the forming process parameters are optimized, such as a pre-powder starting temperature of 155℃, a pre-powder holding temperature of 168℃, a processing temperature of 169℃, and a filling speed of 4 000 mm/s, whereby the formed water retaining plates have a good appearance. The plates have passed the assessment and verification of the water retaining and heat resistance tests, which have laid the foundation for the expansion and application of SLS nylon producing technology in the aerospace industry.