A method for balancing a color wheel. The rotational unbalance vector of a driving motor is measured, including its unbalance amount and direction. The unbalance of a color wheel is adjusted to make its unbalance amount to be the same of the driving motor. The color wheel is connected to the driving motor so that the unbalance direction thereof is opposite to each other to reach an expected balance. The color wheel structure includes a set of color filter and a ring, before starting the assembly, adjusting the unbalance vector of the ring and motor shaft first, and then to assemble it and make the unbalance vectors opposite.