Objective: To investigate reliability and immediate stability of single lumbar laminoplasty. Methods: 6 lumbar specimens from L1~5 were used in this study. 6 different models were made: A，control(intact)；B，laminoplasty fixation with titanium miniplate；C，laminoplasty fixation with cross Kirschner wire；D，laminoplasty fixation with double 1-0 suture silk；E，laminoplasty fixation with titanium miniplate, without the posterior ligament complex, and F, posterior vertebral canal decompression, without the posterior ligament complex. the specimens were placed on the 3-D spine motion test machine loaded with 10N to get the range of motion (ROM)of 6 freedom degrees(flexion and extension, left and right bending, left and right axial rotation) of L3~4 segments. Results: ROM of six models were 7.03±2.24，7.16±2.95，7.4±2.47，8.55±3.31，11.1±2.81，10.82±2.82 for bending and extension, 8.8±2.68，8.81±2.42，8.76±1.81，9.55±3.15，9.12±1.97，9.49±2.78 for left and right bending, and 3.96±2.03， 5.04±2.82，4.99±2.6，5.56±2.47，6.03±2.62，6.03±2.73 for left and right rotation respectively. Laminoplasty without the posterior ligament complex and posterior decompression increased spine ROM compared with that of other three laminoplasty keeping the posterior ligament, especially for bending and extension status (P<0.05). Suture silk fixation increased the ROM of spine compared with that of control and other two fixation groups (P<0.05). Conclusions: Tatanium miniplate and cross Kirschner wire fixation during laminoplasty with keeping or repairing posterior ligaments can maintain the better spine stability compare to that of laminoplasty without keeping the posterior ligaments .