band flexibility means how many types of crop can be selectively and productively grown in a land.It is an important index of the land productivity and land capability.Pvesearch in this field is still in its starting stage.This article introduced and proposed a mathematic model for calculating the Land flexibility index.The model was used to calculate and analyse the land flexibility indices of some representative land units under different conditions of climate and other soil-forming factors in Canada.The results indicated that the model was reasonable and applicable.furthermore,it was also used to calculate and analyse the land fixibility indices for whole Canada (755 map units in all),especially for the three prairie provinces in Canada.The results accorded with the actual situations of both whole Canada and the prairies.This research also showed that this madel could be taken as a quick way to search and evaluate agricultural lands in a province or in a nation,and could be used to macroscopically master the potentials,over-reclamation or under-reclamation of lands in a province or in a nation.So it is an adrnin.istering tool for readjusting and realigning lands in a country-wide scope.Moreover,this research also revealed that establishing a soil information system and bringing it into full play would be very important and urgent.