A laser diode control circuit loop comprises a reference circuit with a programmable reference current, a first endpoint thereof providing a first voltage and a second endpoint thereof providing a second voltage, according as the reference current passing through the first endpoint and the second endpoint; and a driving circuit, a third endpoint thereof connected to the first endpoint of the reference circuit, a fourth thereof connected to the second endpoint of the reference circuit, a output end thereof providing a driving voltage and an output current, and the reference current of the reference circuit and the output current of the driving circuit are as direct ratio. With regard to the operation field of the laser diode driving circuit, the operation limitation within low voltage can be got over, according as the output current from the reference current matching.