Geophysical exploration work in the Yangbajing geothermal field might be divided into two stages.Employing the direct current method as the main method with the help of ground gravity and magnetic survey; the first stage aimed at delineating spatial limits of the thermal reservoir. The second stage was designed to meet the demand of deep thermal reservoir exploration and adopted suh methods as magnetotelluric sounding; frequency electromagnetic sounding; microseismogram sounding and ground noise survey in combination with gravity; magnetic and electric sounding data as well as geochemical and geological data. Such an integrated study yielded some' new achievements: the heat source of foe thermal field is further proved to be a localized magma chamber at the depth of more than 10km; the deep thermal reservoir is mainly located in the north of the thermal field and occurs in the shatter fissure zone at the depth of some 1000 - 3000m with the temperature evidenced by borehole data to be in excess of 300℃; the shallow thermal reservoir in the southern district of the thermal field is a secondary reservoir: the thermal fluid came mainly from the depth of the northern district; and when percolating southeastward; the thermal fluid was mixed with large quantities of cool groundwater; thus reducing the temperature but increasing the flow rate.