An adaptive method to determine chip rate is proposed for laser communications based on diffuse in a close space. Compared with conventional laser communications in free space, the method adds a test process of chip rate in the beginning phase of communication. In the process, equipment 1 and equipment 2 communicate using fixed low chip rate, and a series of test data composed of alternant appearance of signal “1” and signal “0” is transmitted from equipment 1 to equipment 2. In virtue of the accepted data in equipment 2, the persistence time of signal “1” and appropriate chip rate of communication in existing circumstances can be calculated. After equipment 2 transmits the chip rate to equipment 1, the two equipments will communicate using the new chip rate. There are two merits about the laser diffuse communication system using the aforesaid chip rate. The first is neither resulting in errors due to delay of laser diffuse nor wasting communication resource due to low chip rate, and the second is that communication circumstance needs not to be considered nor the chip rate can be obtained automatically by software.