The perception of novel tones is influenced by previous experience with a tonal system. While cross-linguistic tonal acquisition has been examined in previous work, the situation of bidialectal tonal speakers has received less attention, and little is known about how two established tonal systems interact and shape the perceptual space. We examined Chengdu Mandarin-Standard Mandarin (CM-SM) bidialectal and Standard Mandarin (SM) monodialectal speakers’ perceptions of tones across dialects. Both CM and SM have four tone categories with cross-dialectal one-to-one phonemic correspondence. Importantly, each tone category has different pitch realizations between the two dialects. Therefore, in the case of CM-SM bidialectal speakers, both phonetic and phonological factors could potentially play into cross-dialect perception. The results from a pair-wise dissimilarity judgment task show that for both groups, acoustic-phonetic similarity was the driving factor in dissimilarity judgments. However, the bidialectal group’s judgment was also influenced by phonological factors. Compared to the monodialectal group, the bidialectal group perceived two tones with cross-dialectal phonemic correspondence as more similar to each other. This study shows that bidialectal speakers categorize their tonal systems differently from monodialectal speakers, even when their two tonal systems differ primarily at the level of phonetics.