Experimental researches on the stability of the point light source in the “three point method”and the factors affecting the transmission of light beam were carried out,and a 21m long experimental arrangement for laser alignment with an accuracy of ±0.6～0.8μm (or ±3～4×10-8) was developed.The tide change of an artificial fault was measured with the arrangement,the maximum change for level displacement in 24 hours for a small tide period is within 11μm.The potentia- lity for prediction of earthquake,measurement of dam deformation and adjust- ment of particle accelarators are analyzed,effects of generalized relativistic temporal-spatial bending on aligning light beam are discussed.