We conducted a detailed radiative transfer modeling of the dust emission from the circumstellar disk around HL Tau. In addition to the ALMA images at Band 3 (2.9 mm), Band 6 (1.3 mm) and Band 7 (0.87 mm), the most recent VLA observations at 7 mm were taken into account in the modeling efforts. A simulated annealing algorithm was invoked to search for the optimum model. The best-fit model shows that most parts (i.e., > 8 AU) of the disk becomes optically thin at this long wavelength, which allow us to constrain the dust density distribution, particularly in the inner region of the disk. We found that disk models with a homogeneous grain size distribution cannot explain the observed images at different wavelengths simultaneously, which implies that dust evolution has already taken place in the disk at a relatively young (i.e., ∼1 Myr) age. We compare the midplane temperature distribution, optical depth and properties of various dust rings with those reported in the literature. Using the Toomre parameter, we briefly discussed the gravitational instability as a potential mechanism for the origin of the dust clump in the first bright ring.