Based on the analysis of the action of surfactant in granite grinding with diamond disk, the effects of the grinding coolant with different surfactant and concentration were studied in belt grinding of granite. The influences of different factors on belt grinding were analyzed and the machining parameters are optimized by experiments. The results show that belt removal rate was increased greatly using grinding coolant with surfactants. The grinding speed and grit mesh of belt and the rotating speed of table will affect the functions of surfactant in belt grinding process. Introduction Because of excellent performances of granite, such as high hardness, low coefficient of expansion, non-conductivity, non-magnetism, granite has widely been used in precise measurements and precise parts of high precise machine, including body, slide way and spindle, etc. There exists low efficiency and poor quality in the traditional granite machining. Belt grinding was developed in the 1960s, and it is highly efficient, with steady speed, highly grinding precision and low cost. Because belt grinding is a kind of elastic grinding, it has the mixed functions of grinding, rubbing and polishing. The excellent grinding performance of belt grinding of stone has been proved [1,2]. In the stone drilling and cutting process, water or coolants with surfactant are often used to lubricate, and discharge chips. The reports focused mostly on the effects of surfactant on cutting force and tool wear in the cutting process, and on drilling speed in the drilling process [3-5]. The mechanism of surfactant in granite grinding has been studied [6], which indicates that high removal rate can be obtained through the actions of surfactant. Based on the previous research work, the application of surfactant has been also studied in the belt grinding of granite. Experiments Grinding tests were performed using a plane belt-grinding machine with loading board and rotating table. The main minerals of the granite are plagioclase (55%), augite (45%), magnetite (2-3%), and little quartz (1-2%). The granite samples were cut into 100mm×100mm×20mm plates, and were fixed on the grinding machine table. Carborundum belts, with grit mesh 120#, 240#, 400#, 600#, was used as grinding tools in the experiment. Three kinds of surfactants, cationic surfactant, non-ionic surfactant and anionic surfactant were chosen. Micro-hardness and Roughness of Granite Surface The micro-hardness of granite surface was measured with Vickel hardness test. In the measurement, it was difficult to find contact surfaces without breakages because the surface of augite has many initial cracks. The micro-hardness of plagioclase granite was looked as the surface micro-hardness of granite. Fig.1 shows the measurement results. Surface roughness of granite under the different grinding conditions is illustrated in Fig.2. The grinding conditions were grit mesh 240#; speed of belt 15m/s; rotating speed of table 50 rpm in Fig.1 and Fig.2.