As we all know, the research and development (R&D) is crucial for enterprises. How to choose the R&D project is an important research topic, and at the same time, it is also a typical multi-attribute decision-making (MADM) problem. In this paper, we propose a novel MADM method for selecting the Yunnan Baiyao’s R&D project of toothpastes. Firstly, we use T-spherical fuzzy sets (T-SFSs) to express the evaluation information of the toothpastes from decision makers to overcome the shortcomings existing that the traditional information form may cause information distortion. Secondly, we extend the generalized Maclaurin symmetric mean (GMSM) operator to T-spherical fuzzy environment and propose the T-spherical fuzzy GMSM operator (T-SFGMSM) and the T-spherical fuzzy weighted GMSM operator (T-SFWGMSM), where these operators are suitable for the situation which the input information is interrelated. Further, we put forward a novel MADM approach for selecting toothpaste product based upon the T-SFWGMSM operator, which can not only handle a more extensive scope of fuzzy information, but also process the interrelationships between multiple attributes. Lastly, we solve a R&D project selection problem for Yunnan Baiyao Co., Ltd. by the proposed method and make a detailed comparative analysis with other MADM methods to demonstrate the effectiveness and superiority of the novel approach.