Micro tremor measurement of Building of Thapathali in Kathmandu valley was analyzed to determine the natural frequency of the building. Natural Frequency of the building was determined from the Fourier spectra and its value is 2.48 Hz and 2.40 Hz in the longitudinal and transverse direction respectively. Regarding the damage in building due to Gorkha EQ-2015 three types of modal were prepared for sap Analysis. Among them, 1st modal of the building was prepared without any damage that resembles the normal building before EQ and its obtained frequency is 2.372 Hz. Similarly, 2nd modal of the building was prepared with considering the damaged part of the column due to EQ. We have reduced the stiffness of the cracked section by 70% of its original value and modal is prepared and its obtained frequency is 2.358 Hz. Finally, the third modal was prepared according to retrofitting condition and its obtained frequency is 2.521 Hz. Similarly, codal procedure was also performed to determine the frequency of the building and its value was found to be 2.207 Hz.