A method for implementing transmission performance detection includes: after successively receiving data packets whose sequence numbers are N1 and N2, determining, by a detection apparatus, that N2 is greater than N1 and that N1 and N2 are inconsecutive; after receiving the data packet whose sequence number is N2, receiving a data packet whose sequence number is M1; and when determining N1 =RTT, determining that the data packet whose sequence number is M1 is a retransmitted packet corresponding to an upstream packet loss, where T1 is a time for receiving the data packet whose sequence number is N2, T2 is a time for receiving the data packet whose sequence number is M1.