Objective  To analysis the diagnosis maneuvers of lateral semicircular canal benign positional paroxysmal vertigo (BPPV) and to explore the diagnostic mechanism.   Methods  The three-dimensional BPPV labyrinth model was established based on the physical engine. The otolith in different positions of the lateral semicircular canal was set up. The otolith movement in different positions during the horizontal roll test was analyzed, and the induced nystagmus could be inferred.   Results  Horizontal roll test nystagmus manifestations were diverse, including bilateral ageotropic nystagmus, which could be judged as otolith in ampullary and crista, and weak side of nystagmus was the affected side; bilateral geotropic nystagmus could be judged as otolith in the long arm of the lateral semicircular canal, and strong side of nystagmuss was the affected side; Ageotropic nystagmus in one side and geotropic nystagmus in another side, considering otolith in ampullary of long arm. The horizontal roll test may restore otolith to utricle and reduce the sensitivity of the diagnostic tests. The result  of 10 repetitions were consistent.  Conclusion  Sixty degree horizontal roll test effectively corrects the defects of 90 degree horizontal roll test. The analysis of diagnostic tests based on the physical engine is of great significance for us to understand the diagnostic mechanism of BPPV in the lateral semicircular canal and to improve and innovate diagnostic maneuver.