Display omitted •A metal and catalyst free 1,3-dipolar cycloaddition has been developed.•Gram-scale reaction could be achieved.•Fully substituted pyrazole can be obtained by easy transformation. A metal and catalyst free 1,3-dipolar cycloaddition reaction of azomethine imines with internal alkynes has been developed. Various N,N-bicyclic pyrazolidinones could be prepared quickly under microwave irradiation in moderate to excellent yields (up to 96%). A wide range of azomethine imines and electron-deficient internal alkynes were applicable to this reaction. In addition, gram-scale reaction could be achieved and fully substituted pyrazole can be obtained by easy transformation of N,N-bicyclic pyrazolidinone. This environment friendly dipolar cycloaddition is remarkable for its simplicity in conditions and wide structural diversity.