Abstract: As the phenomenon of arbitrary interpretation, expansive interpretation and interpretation deviating from the contracting states' intention of investment treaty often occurs, the guidance and restriction of the arbitral tribunal's power is particularly important. State parties can clearly define the status and role of the treaty law convention (TLC) in investment treaties. Using TLC to guide and restrict the arbitration tribunal's treaty interpretation behavior, strengthening the combination of text interpretation and teleological interpretation, giving full play to the auxiliary role of effective interpretation method and reasonable interpretation method, and actively applying the systematic integrated interpretation method and the evolution interpretation method will help the arbitral tribunals to interpret the treaty provisions strictly, apply the law correctly, reason rigorously and consider the relationship between investment treaties and other international laws as well the balance between the interests of all parties concerned with investment. All these methods are helpful to promote the accurate, true, effective and reasonable interpretation of investment treaties.