  The unusual extinction curves of SN 2010jl provide an excellent opportunity
to investigate the properties of dust formed by core-collapse supernovae. By
using a series of dust models with different compositions and grain size
distributions, we fit the extinction curves of SN 2010jl and find that a
silicate-graphite mixture dust model characterized by exponentially cutoff
power-law size distributions can well reproduce its unusual extinction curves.
The best-fit results show that the extinctions derived from the dust models are
consistent with the observed values at all epochs. However, the
total-to-selective extinction ratio $R_V$ is about 2.8 - 3.1, which is
significantly smaller than the value of $R_V \approx 6.4$ derived by Gall et
al. The best-fit models indicate that the dust grains around SN 2010jl are
possibly composed of small-size astronomical silicate grains and micron-size
graphite grains. In addition, by fitting the optical to mid-infrared spectral
energy distribution, we find that the dust mass around SN 2010jl increases with
time, up to $0.005\,M_{\odot}$ around 1300 days after peak brightness, which is
consistent with previous estimates.
