A systematic optical emission spectroscopy (OES) study was carried out to enhance the deposition rate of microcrystalline silicon (muc-Si:H) with conventional r.f. plasma-enhanced chemical vapor deposition (r.f. PECVD), Among the various plasma parameters, the combination of total pressure, r.f. power, electrode distance and cathode heating was effective to promote the deposition rate without deteriorating the film crystallinity. Strong correlations among the OES intensity, SiH, intensity ratio, I-H alpha/I-Si*, deposition rate and Raman intensity ratip, Imuc-Si/Ia-Si were confirmed in the case of r.f. SiH4 and H-2 PECVD. A relatively high deposition rate was achieved of similar to 5 A/s in the muc-Si:H film growth by optimizing the deposition parameters. The effects of higher pressure, higher r.f. power, inter electrode distance and cathode heating (SiH4, gas heating) are demonstrated in the growth of muc-Si:H from strong H-2-diluted SiH4 by a conventional r.f. glow discharge.