The invention relates to a method for searching for a channel within a frequency band range, which includes the following steps: according to an initial frequency as a starting point, whether or not a first condition is satisfied is detected at an interval of a first frequency away from the initial frequency, among which, the first condition is that a level synchronous signal is continuously detected to predetermined times; if the first condition is satisfied, the frequency in the current time is then recorded as the frequency of an entry point; whether a frequency signal exists or not is detected at the interval of a second frequency away from the frequency of the entry point, among which, the interval of the second frequency is shorter than the interval of the first frequency; and lastly, the frequency of the entry point is set as the initial frequency after renewed and the steps are executed repeatedly until frequency signals within the frequency band range are searched completely.