The present invention discloses a multiple-nuclide gamma imaging system and method and belongs to the field of medical imaging. The multiple-nuclide gamma imaging system comprises a multiple-nuclide tracer injection module, a multi-nuclide scintillation crystal detector module, a configurable circuit module and an image reconstruction and imaging module. The multiple-nuclide gamma imaging method comprises the following steps: S1, starting the imaging system, setting acquisition time of the imaging system, and injecting 11C, 13N, 15O and 18F labeled compounds into an imaging object; S2, obtaining a decay event emission gamma pulse data set by positioning a gamma detector; S3, outputting an electrical signal (scintillation pulse) by a silicon photomultiplier; S4, conducting time discrimination, energy discrimination, data acquisition and coincidence processing by a detector; and S5, displaying images in a tomographic manner by a computer. The disclosed multiple-nuclide gamma imaging system and method can obtain more comprehensive data than the prior art, comprehensively analyze multi-molecule events and related influences, reduce requirements on the total gamma photon counting, reduce irradiation risks on organisms and improve a signal-to-noise ratio of reconstructed images.