Objective: To explore comorbidity and factors associated with mental disability in physical disability among persons aged 15 years and over in China, so as to provide scientific evidences for prevention to multiple disabilities. Methods: Using unconditional logistic regression analysis, the data of the Second National Sample Survey on Disability was analysed to explore risk factors associated with mental disability comorbidity in physical disability. Non-parametric Mann-Whitney U rank-sum test was used to compare impact of disability comorbidity on both mental disability and physical disability. Results: The prevalence of mental disability attributed to any mental disorder in physical disability was 9.4%. The comorbidity of individuals with severe disability and functional impairment were higher in physical disability comorbid with mental disability than those in people with physical disability only and mental disability only (P<0. 05). The risk factors associated with mental disability comorbidity in persons with physical disability included female (OR = 1.60, 95% Cl: 1.31 - 1.96), 30 - 44 (OR = 1.98, 95% Cl: 1.26 - 3.10) and 45 - 59 years of age (OR = 1.69, 95% Cl: 1.06 - 2.68), being unmarried( OR = 2.52, 95% Cl: 1.85 - 3.44), being widowed or divorced( OR = 1.53, 95% Cl: 1.20 - 1.95), urban( OR = 1.26, 95% Cl: 1.02 - 1.54) and persons with severe disability(Grade I, OR = 2.30, 95% Cl: 1.63 - 3.26; Grade II, OR = 1.76, 95% Cl: 1.34 - 2.30; Grade II, OR = 1.43, 95% Cl: 1.14 - 1.79). Conclusion: The comorbidity of mental disability in physical disability is higher than that in general population. Disability comorbidity aggravates degrees of disability and functional impairment of physical disability and mental disability. [ABSTRACT FROM AUTHOR]