OBJECTIVE To evaluate the short-term clinical curative effects, cost effective ratio between ProFile nickel-titanium rotary preparation technique and stainless steel hand K-files preparation technique in molar root canal therapy. METHODS All patients were randomly divided into two groups: 49 cases were prepared with stainless steel hand K-files in routine preparation technique; 45 cases were prepared with ProFile nickel-titanium rotary instruments in step-down technique. The clinical symptoms and cost were recorded. The data was analyzed by SPSS11.5 software package. RESULTS The satisfactory rate of clinical effect of the NRPT group was significantly higher than SSPT(P = 0.034); The mean cost of the NRPT was significantly higher than SSPT (P = 0.001), the satisfactory rate of NRPT in severe curve subgroup was significantly higher than that of SSPT (P = 0.007), however, the C/E of NRPT was 394.52 Yuan less than SSPT. The former was 192.04 Yuan more than the latter in light curve subgroup. When it was classified by periapical condition before treatment, the satisfactory rate of NRPT was significantly higher than SSPT in negative subgroup yet (P = 0.012), the C/E of the former was 32.32 Yuan more than the latter; nevertheless, the C/E of the former was 376.47 Yuan more than the latter in positive subgroup; CONCLUSIONS It is better to prepare with ProFile nickel-titanium rotary preparation technique in severe curve subgroup, however, the light curve subgroup should be prepared with stainless steel hand K-files preparation technique. To patients with positive periodontopathy, SSPT would save the cost of treatments, nevertheless, NRPT group have a higher short-term recent effect.