  In this letter, we report the dark matter search results from the
commissioning run and the first science run of the PandaX-4T experiment. A
blind analysis is carried out on the entire data set. The data processing is
improved compared to previous work, unifying the low-level signal
reconstruction in a wide energy range up to 120 keV. With a total exposure of
1.54 tonne$\cdot$year, no significant excess of nuclear recoil events is found.
The lowest 90% confidence level exclusion on the spin-independent cross section
is $1.6 \times 10^{-47} \mathrm{cm}^2$ at a dark matter mass of 40 GeV$/c^2$.
Our results represent the most stringent constraint for a dark matter mass
above 100 GeV$/c^2$.
