Propagation of light in materials with inhomogeneous refractive index， such as biological tissues， is affected by multiple scattering， resulting in complicated interference patterns， known as speckle［1］， which limits the application of conventional optical method and makes it hard to focus and image in such medium. Recent years， many efforts have been devoted to developing methods such as wavefront shaping and ghost imaging so as to enable focusing and imaging objects behind or inside scattering media［2-6］. In 2007， VELLEKOOP I M［7］ optimized the input laser speckle by maximizing the input laser intensity in the scattering medium， to focus on a specified position in the scattering medium. However， most of them are invasive since they require either the presence of a detector［8-9］ or a “guide star”［10］ to be placed behind or within the scattering medium. In 2012， BERTOLLOTII J et al.［11］ proposed an optical method which first verified the possibility of non-invasive imaging through the scattering medium. It realized the imaging of a fluorescent object hidden behind a thin scattering layer by collected the total fluorescence using a bucket detector， without access to the region behind the scattering medium. This method was later extended to noninvasive imaging of scattering media using spatially incoherent light and ordinary cameras［12］. While， since it relied on the speckle correlation， this technique is limited by optical memory effect. Based on the concept of non-invasive detection， KATZ O et al.［13］ proposed a nonlinear wavefront shaping method to achieve focusing by maximizing two-photon fluorescence intensity. In this method， the nonlinear signal from the fluorescence object is obtained， and the maximum fluorescence is achieved when the excitation light is converged as closely as possible. However， the nonlinear signal needs to use ultrafast laser source， which is not suitable for continuous wave laser imaging. Since then， different wavefront shaping technologies based on linear focusing［14-15］ used in linear fluorescence microscope technology， speckle correlation［16-17］， and transmission matrix［18］ have emerged in succession. However， these methods tried to converge the excitation light as closely as possible by monitoring the total fluorescence intensity resulting in a bad focus. In recent years， a linear focusing method using speckle variance optimization was proposed［19-20］ which can solve the problem to some extend.