China usually limits visas-on-arrival to "emergency" or very quickly developing business situations where there is no time to get a regular visa. Typically, there will need to be an Chinese host/sponsor providing paperwork and backup to expedite this. And it will be of limited duration, generally enough time to attend to the business at hand (contract signing, funeral, delivery of emergency supplies, etc.) I thought that China also used to let citizens of favored nationalities do visa-on-arrival, if there was no Chinese Embassy located in their home country and if they had some advance paperwork/arrangements made. Not sure if this is valid anymore though.

For normal visitors, find a way to get your visa in advance. There are some limited-use, 5-day permits issued to some nationalities at Special Economic Zones like Shenzhen and Zhuhai, but they are good for those localities only and usually apply to people arriving at land borders.