A laser driver circuit for burst mode transmission is equipped in a transmitter at a client side within a P2MP (Point to Multipoint) optical network. The laser driver circuit utilizes a laser driver chip for a continuous mode. The selected laser driver chip is capable of working under an open-loop situation. A burst signal containing time slot information is fed to the switch connected to the laser driver chip. If the burst signal is enabled, a resistor of a predetermined value is connected to the laser driver chip via the switch so that normal driving current is generated for data transmission. If the burst signal is disabled, another resistor whose value is greater than the predetermined value is connected to the laser driver chip via the switch so that no or almost no driving current is generated, thereby avoid the signal collision problem of the channel shared by multiple clients.