Chinese Visa for my girlfriend

I am about to travel to Nantong for work, where i will be stationed for 4 months. The company i am working with will be inviting me to the country, so i will have no problems receiving a Z type. I would like my girlfriend to accompany me for these 4 months. What will be the best way to permit her entry into China and what will be the longest time she will be able to stay in China. She currently has no plans to work in China. Thanks.