An online measurement method and measurement apparatus for a residual stress of a conductive thin-film material (1). The method comprises: using an electrostatic driving pull-in principle to design a measurement structure; using synchronous processing to control relevance between parameters of two measurement members (104-1, 104-2); by means of limiting relevant parameters of total strain energy of the two measurement members (104-1, 104-2), constraining a partial differential equation set of the total strain energy thereof; and by means of solving the partial differential equation set, obtaining unknown numerical values of residual stress σ0 and Young's modulus E of the two measurement members (104-1, 104-2).