Objective To test the reliability and validity of World Health Organization Disability Assessment Schedule (WHODAS 2.0) for assessment of functioning for people with chronic diseases. Methods From December, 2017 to June, 2018, 346 patients with chronic diseases who received rehabilitation interventions in Huadong Hospital-Jing'an District Rehabilitation Medical Association were selected and evaluated with WHODAS 2.0, and re-evaluated after two weeks. According to the actual use of clinical rehabilitation, in order to improve the accuracy of functional measurement, the items had been added in the second domain Getting Around including Handling, Moving and Manipulating Objects, while added in the third domain Self Care including Caring for Body Parts and Toileting, and added in the fourth domain Getting Along with People including Establishing Formal Social Interpersonal Relationship, with a total of 40 items. The content reliability and structural validity of the scale with four items added were verified by internal consistency reliability, test-retest reliability and confirmatory factor analysis. Results The Cronbach's α coefficient of the internal consistency reliability was 0.981, the Pearson coefficient of the test-retest reliability was 0.977 (P < 0.001). The final model of the scale with confirmatory factor analysis had good structural validity: the standardized factor loads between potential variables and corresponding measurement indicators were 0.710-0.960, and the standard errors were 0.023-0.066; Chi square degrees of freedom < 5, root-mean-square error of approximation < 0.1, standardized root mean square residual < 0.08, the comparatice fit index, normal of fit index, relative fit index, incremental fit index and Tucker-Lewis index all > 0.9; the reliability coefficients of the observed variables were > 0.5, the combined reliability of each potential variable > 0.6, and all the average variance extraction of each potential variable > 0.5, all P < 0.001, absolute value of the standardized residual < 3, Modification Index < 4. There was significant difference in the total score and scores of domains among the patients with different diseases (F > 10.21, P < 0.001). Conclusion WHODAS 2.0 can be used as an assessment tool for the overall health and functioning for people with chronic diseases. Each item, including four new items added, had good content reliability and structural validity.