Objective To develop the Professional Identity Scale for Nurses Involved in "Internet+Nursing Service" and to test its reliability and validity. Methods Based on the framework of Social Identity Theory, an initial draft of the scale was constructed through literature review, group discussion, and Delphi method. Exploratory factor analysis was conducted in a pilot survey involving 239 nurses who were in "Internet+Nursing Service", and then confirmatory factor analysis was run in a second survey involving 417 nurses in the same service. Results The Professional Identity Scale for Nurses Involved in "Internet+Nursing Service" included four dimensions with a total of 25 items.Four common factors were extracted by exploratory factor analysis, explaining 86.543% of the accumulated variations.The scale-level content validity index （CVI） was 0.920, and the item-level CVI ranged from 0.800 to 1.000.The Cronbach′s α coefficient, the split-half reliability coefficient, the test- retest reliability coefficient of the scale was 0.987, 0.957 and 0.876, respectively. Confirmatory factor analysis showed that the four-factor model fitted well （χ2/df=2.216,GFI=0.904,RMSEA=0.041,RMR=0.035,CFI=0.916,NFI=0.928）. Conclusion The Professional Identity Scale for Nurses Involved in "Internet+Nursing Service" that was developed based on Social Identity Theory has good reliability and validity, and can be used for the evaluation of professional identity of nurses in "Internet+Nursing Service" in China.