From the perspective of both development and society，this paper took into consideration the rapid development of society and new demand for both national development and science popularization at grassroots level. Based on current research findings，the composition and administrative levels of grassroots were analyzed and the definition，attribute and characteristics of grassroots were discussed. Also the concept of science popularization at grassroots level was proposed from the perspective of development and its connotation and function were analyzed. Based on the analysis of the seven existing modes of science popularization at grassroots level，and considering the strategic demand from the prospective of development and the envisaged smart science popularization，the mode of science popularization at grassroots level was proposed，which is smart，interactive and guided. Based on the combination of both social resources and power，the position and role of government were clearly defined. The contents of science popularization at grassroots level can be divided into two groups according to different demands，namely the basic one and innovative one. With the help of big data analytic tools，explicit and tacit demand for science popularization of different audiences were coordinated. Finally，taking into consideration the influences of the Internet on science popularization from the perspective of development，eight major mechanisms were proposed to facilitate the implementation of the mode of science popularization at grassroots level. The eight major mechanisms are as follows：the organizational mechanism for socialized great science popularization，the tracing，analyzing and forecasting mechanism for demand，the participation mechanism which involves crowd-funding and crowd sourcing，the co-building and sharing mechanism for resources，market oriented management mechanism for venues，internet-based management and motivation mechanism for staffing，and the decision and evaluation mechanism based on big data analysis.