Visa for Wife

Hi. I am a PhD student at Fujian University in China. University clearly refused for any facilitation for the entry permit of my wife. I can bear all her expenses including an outside university living room or flat.
Tell me in this case do I need to get the official invitation letter from university for her S1 type. Or invition letter from my side privately will be enough ???
I already mentioned. University refused for any facilitation.
Plz Guide.

Regards.
Waqar