China’s legal provisions on judicial assistance obligations of financial institutions are applied to thirdparty payment institutions by analogy in judicial practice.However, arising from the nature of “payment”, the difference of the nature of virtual account reserves and storage account funds of payment institutions, the behavioral attribute of “payment”, and the infrastructure status of thirdparty payment services in ecommerce all challenge application by analogy.The judicial assistance obligations of thirdpayment institutions should find their own unique theoretical root.As to the construction of judicial assistance obligation, the control power of thirdparty payment institutions in the field of information, property and behavior contradicts their nondiscriminatory obligations due to the status of infrastructure.By reference to the principle of proportionality under administrative law, judicial assistance obligations of thirdparty payment institutions can be constructed through four steps: insisting on its passive nature; basing judicial assistance obligation on the control power of thirdparty payment institutions; emphasizing its supplementary nature, especially compared with that of financial institutions and ecommerce platforms; and giving a second thought before depriving user’s right to usage of thirdparty payment tools.

electronic commerce; internet finance; thirdparty payment institution; judicial assistance; principle of proportionality; right to usage of payment tools; infrastructure