Completing reaction structures in reaction data would make it possible to understand the true molecular flow for the reaction routes in CASP tasks. Although multiple tools such as rule- based reaction templates, atom mapping software, etc have been developed to investigate molecular transformations in reactions, identifying the missing molecules in reactions remains a challenging task, since most of these data-driven tools were developed from the incomplete reaction datasets. The reaction completion challenge could not be fully solved unless a "golden dataset" with comprehensive complete reactions appears. With the limited complete reaction data sources, the objective in this work was to learn from these limited complete reactions and broaden the boundary of the complete reaction space to some originally incomplete reactions, towards the reaction structure completion of the current reaction records.