To investigate SPICE noise model and the behavior of its parameters, 1/f noise of NMOS devices fabricated by BiCMOS process is measured and compared to the various noise models and measured results. For the long channel devices, bias dependence of the drain current noise power spectral density $S_{Id}$ of NMOS is similar to the previous results. Equivalent gate noise power spectral density $S_{Vg}$ shows weak dependence on the gate and drain voltages in long channel NMOS as the previous results. However, it is shown that most of published noise models are difficult to apply to short channel devices. Therefore, in this study, with comparison of our experimental results, we have tried to find the model of 1/f noise, appropriate for our NMOS device fabricated by BiCMOS process.