Posterior decompression surgery was performed on 610 patients (mean age 62 years) with clinically and radiologically defined cervical spondylotic myelopathy (CSM) at Tianjin Medical University General Hospital, between October 2007 and October 2011. After 2-year follow-up, we had a full data sets from 396 patients with normal mood or continued depression during the whole process to be compared. Depression was assessed with the 21-item Beck Depression Inventory. Physical functioning and pain were assessed with the modified Japanese Orthopedic Association (mJOA) scoring system, neck disability index (NDI), and visual analog scale (VAS). There were statistically significant differences from baseline to 2-year follow-up between normal mood (n = 258) and continuous depression (n = 138) groups in mJOA score (6.76 ± 3.12 vs. 1.42 ± 0.56, respectively; p < 0.01), VAS (23.85 ± 20.79 vs. 16.08 ± 19.76, respectively; p < 0.01), and NDI (21.11 ± 11.36 vs. 7.31 ± 2.18; p < 0.05). The adverse consequences of depression are supported by previous findings that patients with depression suffer more unsatisfactory surgery outcome than the patients with normal mood. We emphasize that patients with continuous depression show poorer improvement after posterior decompression in CSM patients with respect to symptom severity, pain intensity, and the disability score than patients without depression at any stage.