This paper introduces a design of FPGAbased baseband signal generator and mainly describes the key technologies, which are the molding filter and arbitrary resampling interpolation ratio. We not only achieve the standard digital modulation format baseband signals, but also gain a 500MHz highspeed data stream and 200 MHz bandwidth I/Q signal through the design of FPGA internal parallel architecture. After applying it to the vector signal generator, we realize the standard digital modulation format vector signals, such as PSK, ASK, FSK, MSK, QAM, and the bandwidth of vector modulation signal is as wide as 400 MHz. Tests show that the EVM of QPSK and 512QAM reaches 0.7% and 1.0% respectively in the case of 4 M symbol rate, meanwhile the frequency response of 400 MHz bandwidth vector modulation signal is less than 1 dB.