Chinese-language scientific journals serve as a principal platform for publishing research outputs and facilitating academic exchange in China. Improving their international visibility is critical to strengthening China’s scientific discourse power. However, the internationalisation of these journals has long been constrained by language barriers and limited multilingual publishing capacity. This study conducts a systematic analysis along four dimensions—language-ecology structure, longitudinal influence trends, phased policy outcomes, and inter-tier differentiation—drawing on CiteScore 2017–2024 reports from the Scopus database and the Chinese Academic Journal International Citation Report (Natural Sciences and Engineering Technology) (2016—2023 editions). The study reports four main findings. First, English functions as the dominant hub of global academic publishing, with all other languages occupying stratified tiers. Chinese-language journals rank first within the third tier, yet only 28.08% are published in more than one language, which is substantially below the multilingual publishing rates of Italian- (68.94%) and Portuguese-language (70.41%) journals in the same tier, indicating a pronounced language-dissemination barrier. Second, CiteScore 2017–2024 data show that the international academic influence of representative non-English-language scientific journals rose broadly, and Chinese-language journals improved most rapidly, with the citation percentile growing by an average of 5.82 percentage points per year and the CiteScore value by 12.25% per year, both the highest among the languages examined. Third, a two-phase comparison anchored to China’s journal-support policy initiatives of 2013 and 2019 reveals that the gains in average citation percentile and CiteScore value achieved by Chinese-language journals in the second phase (a 1.29-fold rise in CiteScore value) significantly exceeded those of other representative non-English-language journals, reflecting the positive effect of national journal-support programmes such as the Excellence Action Plan for China’s STM Journals on the internationalisation of Chinese-language scientific publishing. Fourth, the international influence of Chinese-language journals exhibits a dual pattern of elite leadership and catch-up growth. The journals indexed early in Scopus (up to 2014) maintain substantially higher average international other-citation impact factors and international immediacy indices than later-indexed journals (after 2015) and the full Chinese-language journal pool, though the later-indexed journals are narrowing the gap at a faster rate. These findings point to several actionable priorities. Bilingual and multilingual publishing should be actively pursued, leveraging AI-assisted translation to lower language barriers through extended English or multilingual abstracts and full bilingual text, while maintaining rigorous language review to safeguard publication quality. Stable international dissemination pathways should be built around substantive academic content, multi-platform collaboration, and transnational authorship networks. Journal-support policies should be sustained and coherent, shifting emphasis from expanding journal numbers toward quality enhancement and tiered support for mid- and lower-tier titles through funding, training, and database-onboarding guidance. Finally, journal evaluation frameworks should be reformed to incorporate dynamic growth metrics, rather than relying solely on cross-sectional bibliometric snapshots.