Objective To evaluate the accuracy of measuring the range of motion of the hip joint using a novel inertia measurement unit based hip smart trial system (IMUHST) during total hip arthroplasty (THA) surgeries. Methods IMUHST system was composed of a smart trial head containing multiple electronic sensors and a terminal computer. A phantom pelvis model was used with the right side hip joint reamed to the diameter of 60 mm and a trial cup was inserted. A phantom femur model was broached and a trial femoral stem was inserted to simulate the THA. A 36 mm diameter smart femoral trial head was mounted to the stem and reduced. Hip range of motion was measured by both the IMUHST and CT scan method. The differences between the IMUHST (study group) and the CT scan method (control group) were analyzed, and intra -class correlation coefficient (ICC) was calculated. Results There was no significant difference between the study group and the control group in hip flexion and extension, adduction and abduction, and internal - external rotation (P >0.05), and the ICC value was 0.982. Conclusion The current in vitro study showed that the IMUHST is accurate in measuring hip ROM, and this system is a promising tool in clinical application.