In the process of computed order tracking, traditional method is based on the given analyzed order requirements, and also assumed that the highest order component is known. But in practice, the order component in signal is usually unknown. With regards to this issue, the paper proposed a method using filter to limit frequency and order. A principle on how to choose filter cut-off frequency and angular domain resampling order are deduced in this paper, then the relationship is analyzed between filter cut-off frequency and resampling frequency in time domain. Simulated signals are tried on the method, the results show that it can solve order aliasing problem successfully, and also effectively reduce resampling order.