Cross-border merger and acquisition (M&A) is considered as an effective shortcut for enterprises in latecomer countries to obtain innovative resources and realize technological catch-up. Formal ownership of the M&A resources does not equate to technological capability enhancement, the effective internalization of M&A resources can support the technological capability leap of latecomers. However, the literature lacks sufficient theoretical explanation for the resource integration mechanism of “M&A—technological catch-up”. Using a longitudinal single case study design, the M&A integration practice between Shenyang Machine Tool Group and SCHIESS is taken as the research sample, based on the conceptual system of “intellectual capital” which is closely related to organizational technological transfer and innovation, this paper studies the internal mechanism of “intellectual capital integration—technological catch-up” based on M&A. The research results show that: (1) Technological catch-up based on M&A follows the path of “absorption and imitation—integration and creation—dominant and leading”. (2) The integration of intellectual capital shows the dynamic evolution of “human capital integration dominant—social capital integration dominant—organization capital integration dominant”. (3) The integration effect of M&A catch-up shows the dynamic change of “reverse absorption effect—diversity fusion effect—ability reconstruction effect”.