  When the Galactic Cosmic Rays (GCRs) entering the heliosphere, they encounter
the solar wind plasma, and their intensity is reduced, so-called solar
modulation. The modulation is caused by the combination of a few factors, such
as particle energies, solar activity and solar disturbance. In this work, a 2D
numerical method is adopted to simulate the propagation of GCRs in the
heliosphere with SOLARPROP, and to overcome the time-consuming issue, the
machine learning technique is also applied. With the obtained proton local
interstellar spectra (LIS) based on the observation from Voyager 1 and AMS-02,
the solar modulation parameters during the solar maximum activity of cycle 24
have been found. It shows the normalization and index of the diffusion
coefficient indeed reach a maximal value in February 2014. However, after
taking into account the travel time of particles with different energies, the
peak time was found postponed to November 2014 as expected. The nine-month late
is so-called time lag.
