Sanjiang Plain is an important commodity grain production base in China and the spatial matching patterns of land and water resources in the plain hold the balance of regional food security. In the last few years, the quantity, quality and spatial matching status of land and water resources in Sanjiang Plain have changed obviously, owing to the significant increase of rice planting area in the plain. Thus, for the purpose of evaluating the current spatial matching situation of the land and water resources in Sanjiang Plain correctly, the spatial distribution pattern of the land and water resources was analyzed first of all, next the available water resources were introduced into the study as the characteristic parameter of water resources quantity, and then a measure model for matching patterns of regional land and water resources was constructed from the angle that the available water resources matched the arable land resources. Finally, the matching degree was graded. The results indicated that land and water resources in Sanjiang Plain since 2000 showed a situation on the whole that land resources were abundant while water resources were deficient, and the spatial distribution patterns of the two resources exhibited an obvious dislocation phenomenon, which was no longer the known situation that land and water resources in the plain were plentiful and matching. The matching coefficient of land and water resources in Sanjiang Plain was 0.35×10⁴m³/hm² in 2008, which was far below the national average in the same period (0.56×10⁴ m³/hm²), indicating a poor matching state. In addition, the matching degree of land and water resources had distinct spatial diversity and presented an overall pattern that south and north better than east and west, marginal land better than hinterland, forest zone better than agricultural zone, mountain area better than plain area. Against the characteristics (poor spatial matching degree and distinct regional diversity) of land and water resources in Sanjiang Plain, while constructing water conservancy works, optimum distributing of land and water resources should be conducted simultaneously to increase their spatial matching degree and to guarantee food security of the plain.