Research on fiber optic sensors with Quasi Gaussian beam has been carried out aiming to analyze the beam intensity profile of the light beam, sensor performance and sensor sensitivity to determine cholesterol concentration. The concept of laser beam propagation is guided by an optical fiber bundle in a solution with a cholesterol concentration that varies from 0 to 300 ppm. The detection mechanism of cholesterol concentration is the propagation of the He-Ne laser beam with a wavelength of 632.5 nm through the fiber optic bundle to the cholesterol solution, then reflected using a flat mirror. Reflective waves enter optical fibers through fiber receiving. This signal is captured by a silicon detector (SL-818, Newport) in the form of electrical voltage. The results show that the power profile increases with increasing distance of object shift from optical fiber. After reaching peak output power, the power profil will decrease exponentially with increasing distance. The performance of the shift sensor of the Quasi Gaussian beam optical fiber to determine the concentration of cholesterol achieves high sensitivity, linearity and accuracy with a sensitivity value of 0.08 mV / ppm, linearity of more than 97%, linear range of 0-300 ppm, resolution of 1.76 ppm and standard deviation of 0.14 mV. Sensitivity through mathematical analysis using the Quasi Gaussian beam approach is higher than the sensitivity of the Gaussian beam. Based on the output power profile, sensor performance, sensitivity through the flat mirror reflection field and sensor stability, it can be concluded that the optical fiber sensor using Quasi Gaussian beam can determine cholesterol concentration.