Abstract: The invention relates to method for the efficient expression and purification and application of a recombinant fusion protein of MANNase and homologues thereof and GLP-1. Through genetic recombination technology, soluble proteins are obtained by using high density fermentation of Pichia pastoris to induce secretory expression, followed by isolation and purification by filtration and concentration to obtain high yield of target proteins. The high fermentation expression and simple isolation steps solve the limitations of the current GLP-1 analogs such as low drug yield, high cost and the need for frequent injections. More importantly, the fusion protein has hypoglycemic effect not only by injection, but also by oral administration for hypoglycemia and weight reduction, which has good application value in obese and pre-diabetic patients. It also provides a basis for further research on the mechanism of hypoglycemia and weight loss of mannanase and homologues thereof with GLP-1 recombinant fusion protein.