The invention relates to the technical field of solar cells, in particular to an optimization method of a thin-film solar cell micro-lens structure applied to photovoltaic building integration, whichcomprises the following steps of: constructing an initial glass substrate thin-film solar cell model; by controlling and determining key variables of the micro-lens structure, micro-lens structures ofdifferent shapes are constructed on a glass substrate of the thin-film solar cell, and a thin-film solar cell model of the micro-lens structure is obtained; taking one day of the same date in each month in 12 months, taking two hours as a step length every day, and setting a solar light source model changing along with the sun motion trail within 7: 00-18: 00; aiming at three photovoltaic building integrated scenes of a daylighting roof, a building facade and a sun-shading surface, optimal design is carried out by taking the maximum solar radiation flux of an incident surface of an active layer of the thin-film solar cell as a target, so that the thin-film solar cell micro-lens structure with optimal performance under different scenes is obtained. The optimization method is simple and high in practicability.