Immediately report the loss/theft of passport for the nearest police station, who will issue a proof of loss for you, then take this to your hotel who will add stamped proof of your residency there. Second, go to the nearest embassy or consulate of your home country and apply for a new passport. Finally head to The Public Security Bureau or the local Exit and Entry Administration Bureau for your new Chinese travel visa.
We recommend taking several copies of your passport before your trip and traveling with recently taken passport photos.
Please note that once your passport is reported lost, it is canceled and no longer valid.