A correlation charging method, wherein the method is applied to a charging apparatus, and the method comprises: receiving (S201) a notification message sent by a call session control function device, wherein the notification message carries identifiers of a plurality of application servers, ASs, triggered by a service; determining (S202) whether the charging apparatus receives charging request messages from all the ASs within a preset period, wherein the charging request messages carry the identifiers of the ASs; sending (S203) a detection message to a first AS from which the charging apparatus has not received any charging request message, wherein the detection message is used to obtain a charging capability of the first AS; and receiving (S204) a response message returned by the first AS, and performing correlation charging on the service based on the received charging request messages and the charging capability that is carried in the response message, wherein the performing of correlation charging on the service based on the received charging request messages and the charging capability that is carried in the response message comprises: when the charging capability carried in the response message is offline charging, performing offline correlation charging on the service based on the received charging request messages, or wherein the method further comprises: when the charging apparatus receives the charging request messages from all the ASs within the preset period, performing correlation charging on the service based on all the received charging request messages, and wherein the performing of correlation charging on the service based on all the received charging request messages comprises: when the charging request messages sent by all the ASs comprise at least one offline charging request messages, performing offline correlation charging on the service based on charging request messages sent by all the ASs. receiving (S201) a notification message sent by a call session control function device, wherein the notification message carries identifiers of a plurality of application servers, ASs, triggered by a service; determining (S202) whether the charging apparatus receives charging request messages from all the ASs within a preset period, wherein the charging request messages carry the identifiers of the ASs; sending (S203) a detection message to a first AS from which the charging apparatus has not received any charging request message, wherein the detection message is used to obtain a charging capability of the first AS; and receiving (S204) a response message returned by the first AS, and performing correlation charging on the service based on the received charging request messages and the charging capability that is carried in the response message, wherein the performing of correlation charging on the service based on the received charging request messages and the charging capability that is carried in the response message comprises: when the charging capability carried in the response message is offline charging, performing offline correlation charging on the service based on the received charging request messages, or wherein the method further comprises: when the charging apparatus receives the charging request messages from all the ASs within the preset period, performing correlation charging on the service based on all the received charging request messages, and wherein the performing of correlation charging on the service based on all the received charging request messages comprises: when the charging request messages sent by all the ASs comprise at least one offline charging request messages, performing offline correlation charging on the service based on charging request messages sent by all the ASs. <EOS>