In order to evaluate HTHP properties of the new linear paraffin based drilling fluid (LPBDF), which was recently developed, a series of tests were conducted using selected LPBDF. The evaluation tests include HT aging tests, TH and HTHP rheology tests. Based on the tests, the regression equations were achieved, which can be used to predict the rheological behavior of LPBM under downhole conditions. The results of the study on HTHP properties of LPBM show that LPBDF can be used in deep well.