This application discloses a picture display order determining method which includes: obtaining a decoding order index value of a current picture and a decoding order index value of a previous picture that is adjacent to the current picture according to a decoding order; adding 1 to a cycle identifier value when the decoding order index value of the current picture is less than the decoding order index value of the previous picture; and determining a display order index value of the current picture based on a sum of the decoding order index value of the current picture and a preset positive integer multiple of the cycle identifier value. In this application, the display order index value of the current picture progressively increases based on a display order index value of a picture that is located before the current picture according to the decoding order.