Background: The positive smoker identity construct, which was based on West’s PRIME Theory, affected the smoking prevalence, quit attempts and cessation success. A validated questionnaire which could measure this rich and complex construct may facilitate prediction models of successful cessation. We aimed to develop and validate a questionnaire that assesses positive smoker identity based on West’s PRIME Theory. Method: The initial item pool was developed based on a theoretical framework, empirical literature, existing scales and expert review. The questionnaire was conveniently distributed to 100 smokers. Exploratory factor analysis was utilized to explore domains in the questionnaire. Construct and criterion validity, internal consistency and reliability of the domains were analyzed. Results: The final positive smoker identity questionnaire (PSmoQi) has 26 items under four internally-consistent and reliable domains: Contributory factors, contextual and temporal patterning, identity related to smoking, and behaviour in relation to smoking. The full scale demonstrated good internal consistency (∝ = 0.78), acceptable convergent and divergent validity, and good concurrent validity with the smoker self-concept scale. Conclusion: The current study provides fundamental evidence for the PSmoQi as a valid instrument in research related to smoking cessation and interventional strategy. The PSmoQi contained validated domains which could measure almost a full spectrum of smoking cessation components.