To investigate the effect of 50 Hz 1.8 mT sinusoidal, triangular, serrate and square wave electromagnetic field(EMFs) on proliferation, differentiation and gene expression of osteoblasts in vitro, the newborn rat calvarial osteoblasts were isolated by enzyme digestion and randomly divided into 5 groups after one passage．The EMFs treatment group is exposed to 50 Hz 1.8 mT sinusoidal, triangular, serrate and square wave of EMFs and controls without EMFs treatment. The osteoblasts were exposed to the EMFs for 30 min/(time·day). The cells were observed under the contrast phase microscope each day. The EMFs groups were arranged in spiral appearance after 4～8 days of the EMFs treatment. MTT result showed that sinusoidal wave significantly inhibited osteoblast proliferation, whereas square wave enhanced the osteoblast proliferation. The ALP activity in triangular and sinusoidal wave groups significantly increased (P < 0.01) compared with that in control. The number of calcified nodules, ALP stained result and Collagen-Ⅰimmunohistochemistry tested result are according to the result of ALP activity. There was a common result that sinusoidal and triangular wave significantly increased the Igf, Opg and Runx-2 mRNA expression. The four different wave of EMFs at 50 Hz 1.8 mT enhances the osteoblasts maturation, mineralization and Opg and Runx-2 mRNA expression of the osteoblasts, while sinusoidal and triangular have the strongest effect.