Abstract: Analyzing the engineering geology and hydrogeological conditions of tertiary mudstone in Nanning,and combining with the characteristics of the Nanning subway,geotechnical engineering investigation methods and test projects and the relevant matters on swelling rock area of Nanning rail transit line 1 were discussed Content of detailed geotechnical investigation about space between boreholes and site description on the swelling rock area across in Nanning rail transit line 1 have been presented;it suggested that authentication on rock mineral,water absorption and saturate water absorption test,slake-durability test,swell ability test could be added into laboratory soil test;ground stress test,K₃₀ coefficient of subgrade reaction in field testation,immersion static load field test and horizontal swelling force test is suggested into in-situ test.Some advises aiming at certain geotechnical investigation such as K₃₀ coefficient of subgrade reaction in field test,thermal physics indexes and horizontal swelling force were presented.