With the continuous expansion of central SOEs’ overseas business scale, overseas procurement bidding activities have formed a more complex and concealed risk structure. Bid rigging and collusion have evolved from traditional explicit collaborative behaviors into complex implicit and structured coordination across multiple entities. Against the backdrop of divergent cross-jurisdictional supervision and information asymmetry, experience-based audit approaches can no longer meet risk identification demands. On the basis of systematically analyzing the formation mechanism of bid rigging, this paper constructs a joint identification framework integrating the SDTM standard deviation model and correlation coefficient model to quantitatively identify bid rigging from two dimensions: quotation dispersion and coordination. The model is verified through a typical overseas information technology project. The research results demonstrate that the model can effectively detect abnormal quotation structures and potential collusive behaviors, providing methodological support for the audit governance of central SOEs’ overseas procurement.