Abstract: The present invention provides method and system for lateral scanning interferometry (LSI), which utilizes a reflecting reference element having a tilted angle for generating a tilted optical plane formed by wavefronts of a reference light so that interferometric patterns are acquired according to interferometric lights directed through an objective lens or an array of micro objective lens for analysis while the surface parts of the object enters the coherent range formed by the wavefronts of the reference light during lateral movement and a maximum signal intensity with respect to the acquired interferometric patterns can be obtained while the surface profile of the object has a zero or near zero optical path difference (OPD) with respect to the plane of wavefronts. The present invention is capable of reducing time cost comparing to the conventional vertical scanning interferometric method while enabling the system to be utilized for in-line (in-situ) measurement.