The invention belongs to the field of optics, and particularly relates to a high speed imaging system and method based on pixel optimization coding exposure. The system comprises an objective lens, a first relay lens, a polarization beam splitter, a second relay lens, a spatial light modulator, a third relay lens and an imaging sensor. The objective lens, the first relay lens, the polarization beam splitter, the second relay lens and the spatial light modulator are arranged on a natural light optical axis in sequence. The third relay lens and the imaging sensor are arranged above the polarization beam splitter in sequence. According to the system, a single frame coding exposure image I containing multi-frame imaging information can be obtained. Through studying random videos, an excessive complete dictionary D is obtained, then a restructing algorithm is used, a coefficient alpha is solved, and at last a high resolution multi-frame video image E is obtained. The system and method can avoid the hardware limit on an existing imaging sensor and achieve high speed and high resolution imaging.