A method for implementing transmission performance detection, wherein the method comprises: Obtaining, by a detection apparatus, a time T3 at which the detection apparatus receives a data packet whose sequence number is K1 and that is sent by a sending device through a connection that is based on a reliable transport protocol and that is established between the sending device and a receiving device; when determining that a first target acknowledgment packet sent by the receiving device through the connection is received, obtaining, by the detection apparatus, a time T4 at which the detection apparatus receives the first target acknowledgment packet, wherein the first target acknowledgment packet is a first acknowledgment packet that is received by the detection apparatus and that indicates that the receiving device has received the data packet whose sequence number is K1 or a data packet following the data packet whose sequence number is K1; obtaining another T3 of a second data packet and another T4 of a second target acknowledgment packet, wherein the second data packet has a sequence number K2 and is traveling from the sending device, through the connection, and to the receiving device, wherein the second target acknowledgment packet is traveling from the receiving device, through the connection, and to the sending device, wherein the second target acknowledgment packet is a first acknowledgment packet received by the detection device and indicating that the receiving device has received the second data packet or another packet with a sequence number after K2; computing a two-way latency DRTT between the detection apparatus and the receiving device based on a plurality of groups T3 and T4, and receiving, from the receiving device, at a first time, and when the receiving device is a client device and the sending device is a server, a request message requesting establishment of the connection; receiving, from the sending device, at a second time, and in response to the request message, a response message; and determining a two-way latency (URTT) between the sending device and the detection device as a difference between the first time and the second time. Obtaining, by a detection apparatus, a time T3 at which the detection apparatus receives a data packet whose sequence number is K1 and that is sent by a sending device through a connection that is based on a reliable transport protocol and that is established between the sending device and a receiving device; when determining that a first target acknowledgment packet sent by the receiving device through the connection is received, obtaining, by the detection apparatus, a time T4 at which the detection apparatus receives the first target acknowledgment packet, wherein the first target acknowledgment packet is a first acknowledgment packet that is received by the detection apparatus and that indicates that the receiving device has received the data packet whose sequence number is K1 or a data packet following the data packet whose sequence number is K1; obtaining another T3 of a second data packet and another T4 of a second target acknowledgment packet, wherein the second data packet has a sequence number K2 and is traveling from the sending device, through the connection, and to the receiving device, wherein the second target acknowledgment packet is traveling from the receiving device, through the connection, and to the sending device, wherein the second target acknowledgment packet is a first acknowledgment packet received by the detection device and indicating that the receiving device has received the second data packet or another packet with a sequence number after K2; computing a two-way latency DRTT between the detection apparatus and the receiving device based on a plurality of groups T3 and T4, and receiving, from the receiving device, at a first time, and when the receiving device is a client device and the sending device is a server, a request message requesting establishment of the connection; receiving, from the sending device, at a second time, and in response to the request message, a response message; and determining a two-way latency (URTT) between the sending device and the detection device as a difference between the first time and the second time.