With the increasing need for higher image resolution and amount of data for imaging, it is imperative to develop novel compressive imaging technology with higher information acquiring efficiency. The rise of compressive sensing theory paves the way for compressive imaging. A snapshot compressive imaging strategy by spatial phase modulation is proposed. The feasibility for the imaging strategy is testified by compressive imaging experiment. The spatial resolution and signal noise ratio are analyzed by theory and testified by the experiments, the restrictive relation between them is released.