The invention provides a solar water heater. The solar water heater comprises a heat collector and a water tank connected with the heat collector. The heat collector comprises a first reflection face, a second reflection face and heat collecting pipes. The heat collecting pipes are located between the two reflection faces and fins are only arranged on the outer portions of the heat collecting pipes located on the outermost side of each row. Due to the fact that the fins are arranged on the outer portions of the heat collecting pipes, solar energy can be fully utilized.