The etching behaviour of InP in two chemical etching system is studied with negative Kpp and positive AZ1350J mask in the various concentration Br

2

:CH

3

OH and Br

2

:HBr:H

2

O system

respectively. Etching rate versus Br

2

concentration as well as etching depth versus etching timt is given.These two etching system are very stable for temperature fluctuation. They are available by using negative Kpp and positive AZ135J as resistant mask.The sample surface needn't be coated by sputtered SiO

2

or Si

3

N

4

film as protection mask

it is very convenient to fabricate InP optoelectrical devices. The dependence of etching rate of sample on Br: concentration and etching profiles of sample on crystal orientation are properly explained from the viewpoint of crystallography.