Inspired by the fast take-up of data analytics and modelling in urban planning and design in Chinese cities, this paper aims to address a serious knowledge gap in terms of using data to deliver better policy outcomes rather than technical outputs. Such a knowledge gap is discussed in the wider context of smart city development where technology deployment failed to deliver the expected policy benefits. Lessons thus can be, and should be, learnt from early experiments to prevent the data revolution in planning and design in Chinese cities from repeating the same failure. One of the key arguments is that, in order to leverage the potential power of data and analytics for the urban planning and design industry, a wider theoretical framework is required for rethinking the core role as well as core competence of the planning profession in China. It entails a diversion from the purely technical discourse and the disciplinary / professional silos, towards a socio- technical perspective. A series of propositions are proposed to evoke more critical discussion about the digital agenda for urban planning and design.