We uses improved chemical vapour deposition and drew fibres with InP nano thin films. Based on the hydrogen atom model, we calculate the corresponding size of the InP particle aB=8313 nm. By the quantum size-effect, we calculate the change of the energy band of particles with different sizes and the corresponding light absorption wavelength. From the system testing, the fibres have gain at 906—1044 nm, 1080—1491 nm and 1524—1596 nm. The results showed that the energy level of inner cladding materials creates a red shift when the thickness of thin-film is 5—50 nm. The fibre creates optical amplification.