By comparing routine FBP with algebraic iterative reconstruction, this study exploit the effect of the two SPECT reconstruction techniques on the ratio of Target/Background (T/B) and image noise. The result of research on model and clinical cases showed that the technique of OSEM could increase T/B ratio by 1.5% (heart), 3.3% (bone), 1.4% (brain). No obvious difference in image noise existed between OSEM and FBP. Compared with FBP, OSEM could improve T/B value in bone focus more significantly. Under the same injection dosage, OSEM could increase the speed of image collection by more than one time without changes in image quality and T/B ratio. The result suggested that function and clinical application of SPECT would significantly improved by substituting routine FBP with OSEM.