Abstract: For problem of zero drift of differential pressure densimeter which is susceptible to installation location and fluctuations of measured fluid, bypass installation pipes of differential pressure densimeter was designed and improved, and effect was significant for reducing error caused by shock, preventing clogging of pipelines and advancing service life of diaphragm; digital smoothing filtering algorithm for filtering processing of collected signals was proposed, which improved stability of differential pressure densimeter on the premise that it did not affect measurement accuracy. The practical application results show that the improved differential pressure densimeter can meet requirements of practical application on respects of reliability, stability and accuracy.