In the wireless ultraviolet communication system, the use of appropriate modulation and demodulation technology can effectively improve the system communication quality. In this paper, a fixed-length dual-pulse symmetrical pulse interval modulation (FDPSPIM) method is designed to realize ultraviolet communication, and its symbol structure is analyzed in detail. The modelsimSE 10.1c is used for timing simulation to verify the feasibility of the modulation scheme. At the same time, the hardware description language is used The FDPSPIM modulator and demodulator design based on Field Programmable Gate Array (FPGA) realizes the synchronization processing of sending information through a custom frame structure. The test results show that: based on the built-up ultraviolet light communication experimental platform, the FDPSPIM modulator and demodulator designed by Verilog HDL can correctly identify the original information.