Re: i caught a caterpillar it is green ,spikes on its back,and an orange face.

Since you gave no size, I can only give a range of possibilities, with one 
likely candidate.  Only a few families of Lepidoptera have "spiky" larvae- 
notably the Saturniidae (giant silk moths), Nymphalidae (brush-footed 
butterflies), Limacodidae (slug caterpillars), and some Noctuidae 
(millers).  My guess (based in part on the orange face) is that you may 
have the larva of the Royal Walnut Moth, Citheronia regalis (Saturniidae), 
which is known as the Hickory Horned Devil. Some Saturniidae and 
Limacodidae have venomous spines, but the Hickory Horned Devil is 
harmless, despite its fearsome appearance (See:
http://www.ext.vt.edu/departments/entomology/ornamentals/2-20.jpeg.)
 
 
However, it is wise not to handle spiny caterpillars unless you know for 
sure. 

Reference:

Covell, C. V., Jr. 1984. A Field Guide to the Moths of Eastern North 
America.  Houghton Mifflin Co., Boston. (See Plate 1) 

Mitchell, R. T., and H. S. Zim. 1965. Butterflies and Moths.  Golden 
Press, New York.