The invention discloses a combined enhanced treatment process for low-turbidity high-alga raw water. The treatment process is characterized in that according to raw water, the turbidity in winter is about 5NTU, and temperature less than 5 DEG C, or one liter of raw water contains more than one million algae in summer, and the treatment process comprises the following steps of: settling under the conventional condition by using a flocculation horizontal sedimentation tank or a high-efficiency sedimentation tank, performing air floatation by using an air floatation tank to remove algae, allowing outlet water to flow through an ultra filter membrane further to reduce turbidity and remove algae, adjusting storage by using a clear water tank, and feeding into a water distribution network by using a water feeding pump house. According to the low-turbidity and high-alga characteristics of the water quality of the raw water, the conventional coagulating sedimentation, air floatation, filter and ultra filtration processes are optimized and combined, and the utilization of geothermal resources of plant areas is fully considered, so that an enhanced conventional treatment system is formed. The combined process has the advantages that used land can be saved, the process can be optimized, the geothermal resources can be fully utilized, the production management can be simplified, and the water quality of the outlet water has obvious advantages.