A method, a device, and a system for monitoring quality of an Internet access service of a mobile terminal are provided. The method includes collecting, by a mobile terminal, an IP data packet of an Internet access service, identifying, by the mobile terminal, an Internet access service type corresponding to the IP data packet, performing, by the mobile terminal, deep packet resolution on the IP data packet to obtain a resolution result, collecting statistics, by the mobile terminal, on a key quality indicator of the Internet access service corresponding to the Internet access service type according to the resolution result of the IP data packet, and uploading, by the mobile terminal, the key quality indicator obtained by means of statistics to a network server, so that the network server monitors quality of the Internet access service of the mobile terminal according to the key quality indicator.