The invention relates to the technical field of time service, in particular to a nanosecond time service system. The system comprises a Beidou receiving module, an input signal unit, a transmission signal unit, and an output signal unit. The Beidou receiving module receives the time signal of a Beidou satellite and inputs the time signal into the input signal unit. The input signal unit linearly modifies the time signal, and outputs a second pulse reference time signal whose accuracy meets the requirement of 20 nanoseconds to the transmission signal unit for transmission. The transmission signal unit modifies the obtained time signal and outputs the time signal to the output signal unit. The output signal unit performs discrimination based on time continuity on the time signal, modifies abnormal signals, analyzes the time signal whose accuracy meets the requirement of 20 nanoseconds and outputs the time signal. The technical core lies in performing optimization control on time serviceprocess and crystal oscillator performance, and lies in optimizing an output signal waveform and a transmission path based on the optimization control to achieve 20-nanosecond time service accuracy.