The GaN∶Si films were grown by MOCVD methods on (0001) sapphire substrates by using three different reactors. The opto-electrical and crystalline characterization of GaN∶Si films were measured by photoluminescene (PL), Van der Pauw Hall method and X-ray double crystal diffraction technique at room temperature, respectively. The results indicate that reasonable mixture time of group Ⅲ and groupⅤgas flows is important to improve the quality of GaN∶Si films. When group Ⅲ precursor mixes too early with groupⅤammonia, in other word, the time of the mixture is too long, the ratio of yellow luminescence intensity to band emission intensity is large, and the FWHM of X-ray double crystal diffraction is broad. When group Ⅲ precursor mixes too late with group Ⅴ ammonia, it will cause the opto-electrical and crystalline properties of GaN∶Si films poor due to inhomogeneous mixture even though the parasitic reaction became weak. GaN∶Si films with good opto-electrical and crystalline properties are obtained in B-type reactor.