In the global energy transportation landscape, maritime transport accounts for over 70% of crude oil shipments, making the reliability of its channels paramount to national energy security. Escalating geopolitical tensions have significantly elevated the risk of disruption to critical maritime channels, posing severe challenges to the stability of energy supply chains. To accurately assess this risk, this study employs complex network theory and integrates Automatic Identification System (AIS) trajectory data with vessel capacity weights to construct a global directed weighted network for crude oil maritime transportation, in which critical channels are abstracted as network nodes. Based on this framework, three progressive attack simulation strategies are designed-single channel disruption, compound scenario failure, and optimal disruption sequence-to systematically investigate the multidimensional vulnerability of the network to channel blockages. The findings indicate: 1) Functional differentiation. critical channels exhibit significant functional differentiation. Some are vital for global efficiency; for instance, removing the Strait of Malacca reduces network efficiency by 1.99%. Conversely, others demonstrate structural suboptimality, as exemplified by the removal of the Panama Canal, which paradoxically increases topological efficiency by 2.57%, revealing quantifiable suboptimal paths within the network. 2) Asynchronous vulnerability. The network exhibits asynchronous responses across performance dimensions. While macro-connectivity remains highly robust against single-point or regional failures, the core structure is highly fragile. For example, the network's K-Core value plummets after attacks targeting only four optimal nodes. 3) Non-linear degradation. Under optimal sequence attacks, global network efficiency follows a "U-shaped" trajectory-initially declining before rebounding beyond its original value due to topological reconfiguration. Notably, the collapse of the core structure occurs significantly earlier than the deterioration of overall transmission functionality, with the latter even showing a paradoxical recovery in the later stages of the attack. This study elucidates the underlying failure mechanisms of the global crude oil maritime transportation network under channel blockages, offering a new analytical paradigm and decision-making basis for ensuring national energy transportation security and enhancing the resilience of global supply chains.