http://www.tuicool.com/articles/iaUJjm2
2 ways:
First is a little stupid that trigger frequently by 5 *
H/10 * * * * //every 10 mins
H/1 * * * * //every 1 h
H/x * * * * //every x mins
* * * * * //every minute
Second to trigger by git hooks, call curl to trigger job
github>settings>Hook & Services>Add Service>Github Auto-Deployment>Jenkins(Git plugin)
jenkins hook url: http://xxx/github-webhook
save and test