This paper discusses and explores the different effects of contractual forms on the satisfaction with public transport (PT) at different urban scales. Using public transport systems in 12cities in China as the focus (four large-I-sized cities, four large-II-sized cities, and four medium-sized cities), a measurement model of the passenger satisfaction index (PSI) is constructed and estimated on the basic of the adjusted European Customer Satisfaction Index (ECSI) and Partial least square-structural equation model (PLS-SEM), respectively. Then, a two-stage truncation regression bootstrap model is proposed to assess the different effects between them. The major findings of this study are summarized as follows: (1) different effects of contractual forms on PT satisfaction in large- and medium-sized cities are confirmed. (2) In large-I-sized cities and lager II sized cities, operators supervised by management contracts incite higher PT satisfaction levels than those supervised by gross and net cost contracts. (3) In medium-sized cities, operators supervised by gross cost contracts provide incentives to be the satisfaction compared to those of management and net cost contracts. According to different urban scales, different and appropriate contractual forms and supervision mechanisms should be chosen to regulate public transport services.