Abstract: Rock mass volumetric joint count is one of the most important indexes to evaluate the integrity of rock mass. In - situ measurementmethodsmainly include directmeasurementmethod, spacingmethod, and joint num2 bermethod. All of these measurement methods, p rincip les and their respective disadvantages are analyzed in the paper. Combined with p ractical examp les, it is believed that directmeasurementmethod is relatively accurate, but it requires adequate measurement area that is as large as possible. Data coming from spacing method are slightly low, so it has to be multip lied by correction factor of 1. 05～1. 1; Joint numbermethod is strongly influenced by the azimuth of the surveyed surface. In app lication, it requires enough samp les. Their average value is used as the car2 dinal number. It has to be multip lied by experience correction factor of 1. 4～1. 7.