The invention provides composite mortar and a manufacturing method thereof, and belongs to the field of production of building materials. In the composited mortar, cement, mineral sand, coal ash and glass beads are taken as aggregates, and carboxymethyl cellulose sodium, wood fibers, gelatine powder, a water-retaining agent, a water reducing agent and a water repellent are taken as additives. The manufacturing method comprises the following steps: first, sequentially putting cement, additives, glass beads and coal ash into a reaction kettle, premixing the mixture for a certain time, putting an obtained substance and mineral sand into a stirrer, stirring the mixture and cooling, so as to obtain the composite mortar. The invention provides the composite mortar and the manufacturing method thereof; the composite mortar has the advantages of being safe and non-toxic and reducing energy consumption, is good in peaceability, crack resistance, thermal insulation and waterproofing, high in strength, corrosion resistance and adhesion, light in weight and convenient in construction, is beneficial to mechanical construction, and has the characteristics of saving working hours and lowering construction cost.