This paper investigated the potential acoustic correlates of word stress within a disyllabic tonal sequence, a rising tone followed by a rising tone (Tone2 + Tone2) in Mandarin, based on a large corpus with adequate information of stress patterns and prosodic boundary levels. The results showed that a) For Tone2+Tone2 words, features based on tone nucleus were more effective than that of the whole F0 contour for stress identification. Particularly, three new acoustic correlates of stress were proposed, namely, the F0 change difference, the duration difference and the F0 slope difference of tone nucleus segment between the two syllables. b) These three parameters could serve properly as acoustic cues to differentiate initial-stressed and final-stressed words, as well as initial-stressed and equal-stressed words irrespective of prosodic boundary levels. c) With the increase of prosodic boundary levels, the duration difference of the tone nucleus segment got smaller for the initial-stressed words while getting larger for the final-stressed words, due to stronger enlargement of pre-boundary lengthening at higher prosodic boundary levels. d) At higher prosodic boundary levels, there tend to be a compensation effect between the F0 change difference of the tone nucleus segment and the duration difference within each stress pattern.