Software is the main method of waveform generation in modern virtual signal generator. Aimed at the problem that it is unable to store a large amount of waveform data while the onboard memory is limited, this paper leads to a technology of waveform data streaming, based on AWG PXIe-5442. This technology is a way to generate waveform while storing, the generation can be continuous in a small memory space, and the design of virtual signal generation is accomplished as well as the block flow diagram on this basis. Results show that the technology improves onboard memory utilization greatly, and program based on LabVIEW is efficient and readable.