The invention discloses water and fertilizer irrigation decision making method, device and system and a computer storage medium. The water and fertilizer irrigation decision making method comprises the steps that a spatial interpolation model is built; sample data is obtained from a database, and the sample data is subjected to normal distribution compliance validation on the sample data; a connection weight of the sample data meeting normal distribution and a to-be-measured point is obtained; a to-be-measured point spatial interpolation result is obtained according to the sample data and theconnection weight; the to-be-measured point spacial interpolation result is compared with an expert knowledge base threshold value, experience deviation of water and fertilizer irrigation is obtained,and the experience deviation serves as execution mechanism input to guide the water and fertilizer irrigation system. Accordingly, the actual requirement state of soil water and fertilizer in a certain area can be worked out by building the spatial interpolation model, globally differentiated irrigation and control are conducted accordingly, and then the water and fertilizer irrigation cost can be reduced, the labor cost is lowered, and economic losses caused by irrigation disorder are reduced.