To compare the observation and analyzed on clinic effect of root canal preparation using Protaper ultrasonic machine Ni-Ti files (A group), Protaper hand Ni-Ti files (B group) and standard hand stainless steel K-files (C group). A total of 180 teeth of 159 elder patients were randomly assigned to three groups, and then root canal preparation is taken for 60 teeth of each group respectively.  The Protaper ultrasonic machine Ni-Ti files (A group) made good root canal shape after preparation in a safe and labor-saving method within a shorter time, and removed the debris and contamination level in the root canal thoroughly, It got significant differences from hand Ni-Ti files (B group) and hand stainless steel K-files (C group). As to dentine debris pushed out of apical foramen and solution quality and intraoperative reaction, Protaper ultrasonic machine Ni-Ti file group was less than Protaper hand Ni-Ti file group (P<0.05); Protaper hand Ni-Ti file group was less than stainless steel K-file group (P<0.05). Significant differences existed among them. Compared with Protaper ultrasonic machine Ni-Ti files (A group), hand files (B0C group) can save more labor and time with less medical complications in the process of elder root canal preparation, as well as less substances pushed out of apical foramen. Root canal treatment high success rate.