Ancient Loulan kingdom on China’s Silk Road had disappeared for about 1500 years. Historical literatures recorded that cultivation of Loulan began in BC and supported the kingdom’s flouring of hundreds years. However, any farmland ruin was not found although the ancient Loulan city has been discovered more than 100 years. In the study, remotely sensed, geomorphic and geological evidences of Loulan farmlands were analyzed. Regular and straight boundaries, crossed canals, the gypseous incrustation layer (GIL) overlying on the surface of farmland-like blocks, and large-sized pollens of cultivated grass found in GIL samples demonstrated the existence of farmlands. Field observations revealed that the upper cultivated soil layer overlaid on GIL, i.e. soil horizon A, had been wind-eroded and GIL is the ruined soil horizon B. The new discovery revealed well-developed agriculture of ancient Loulan kingdom. Scale and area of farmlands and the thickness of GIL suggests that history of farmland irrigation lasted for a long time. Underlying fluvial and lacustrine sediments of ancient Loulan city and farmlands deposited during the about 4 - 8kaB.P. period, revealing wet Holocene Optimum and two drought events of about 4 and 8kaB.P. in the Westerlies-dominated northwest China. The Loulan kingdom period was another wet stage and the ecological environment was the typical cultivated grass of oasis near wetland.