A folding chair frame, comprising: a foot tube assembly, wherein the foot tube assembly comprises a front foot tube and a rear foot tube hingedly connected at a top, the rear foot tube is provided with a first connector, the front foot tube is provided with a seat tube, which has one end hinged to the front foot tube and another end hinged to the first connector, and the first connector is hinged to a backrest tube; wherein two sets of foot tube assemblies are oppositely provided, each rear foot tube is respectively provided with a second connector connected to a connecting tube, which has one end hinged thereto and another end hinged to the front foot tube, a front end of each seat tube is respectively provided with a front cross tube, which has one end hinged the seat tube and another end hinged to a bottom end of the front foot tube of the other set of the foot tube assembly opposite to the foot tube assembly in which the seat tube is located; wherein the first connector is a first slider which is slidable along the rear foot tube and the second connector is a second slider which is slidable along the rear foot tube; wherein a set of rear cross tube bodies that are crosswise to each other and cross-hinged is hingedly arranged between the two sets of backrest tubes that are oppositely provided, and the first end of each of the rear cross tube bodies are respectively hinged to one backrest tube, the second end of each of the rear cross tube bodies are respectively hinged to one second connector; wherein the rear foot tube is provided with a limiting member fixedly connected the rear foot tube, and the limiting member limits maximum sliding positions of the first connector and the second connector on the respective rear foot tube in a case that the folding chair frame is unfolded, characterized in that the second connector is provided with a locking assembly that is fitted with the limiting member in a case that the folding chair frame is unfolded, and the locking assembly is fitted with the limiting member to limit the sliding of the respective second connector along the respective rear foot tube and wherein the locking assembly comprises a hook provided on the second connector, a hook mounting hole for mounting the hook is provided on the second connector, a hook mounting shaft and a torsion spring sleeved on the hook mounting shaft are provided in the hook mounting hole, and a limiting groove is provided on the limiting member for locking with the hook. a foot tube assembly, wherein the foot tube assembly comprises a front foot tube and a rear foot tube hingedly connected at a top, the rear foot tube is provided with a first connector, the front foot tube is provided with a seat tube, which has one end hinged to the front foot tube and another end hinged to the first connector, and the first connector is hinged to a backrest tube; wherein two sets of foot tube assemblies are oppositely provided, each rear foot tube is respectively provided with a second connector connected to a connecting tube, which has one end hinged thereto and another end hinged to the front foot tube, a front end of each seat tube is respectively provided with a front cross tube, which has one end hinged the seat tube and another end hinged to a bottom end of the front foot tube of the other set of the foot tube assembly opposite to the foot tube assembly in which the seat tube is located; wherein the first connector is a first slider which is slidable along the rear foot tube and the second connector is a second slider which is slidable along the rear foot tube; wherein a set of rear cross tube bodies that are crosswise to each other and cross-hinged is hingedly arranged between the two sets of backrest tubes that are oppositely provided, and the first end of each of the rear cross tube bodies are respectively hinged to one backrest tube, the second end of each of the rear cross tube bodies are respectively hinged to one second connector; wherein the rear foot tube is provided with a limiting member fixedly connected the rear foot tube, and the limiting member limits maximum sliding positions of the first connector and the second connector on the respective rear foot tube in a case that the folding chair frame is unfolded, characterized in that the second connector is provided with a locking assembly that is fitted with the limiting member in a case that the folding chair frame is unfolded, and the locking assembly is fitted with the limiting member to limit the sliding of the respective second connector along the respective rear foot tube and wherein the locking assembly comprises a hook provided on the second connector, a hook mounting hole for mounting the hook is provided on the second connector, a hook mounting shaft and a torsion spring sleeved on the hook mounting shaft are provided in the hook mounting hole, and a limiting groove is provided on the limiting member for locking with the hook.