The 3D SRAM (three-dimensional static random access memory) will take the place of 2D SRAM (two-dimensional static random access memory), and will be widely used in high performance microprocessor. However, 3D SRAM still suffers from the dangers of soft error. A novel 3D SRAM soft error analysis platform was designed for studying the soft error characteristic of 3D SRAM. The soft error characteristic of the designed 3D SRAM and the original 2D SRAM were analyzed by using our designed platform. It is found that 3D SRAM and 2D SRAM have the same upset cross section, but the soft error of 3D SRAM is more serious than that of 2D SRAM, which makes it difficult to harden 3D SRAM by using error correction codes technologies. At the static test mode, the upset sensitive nodes were only distributed in the memory array of both 3D SRAM and 2D SRAM. It indicates that the logic circuit can’t induce soft error at static test mode.