With the development and utilization of offshore liquefied natural gas, it is increasingly important to study the influence of the heat transfer performance of a spiral-wound heat exchanger under sloshing conditions. This study focused on the effects of different sloshing amplitudes and sloshing periods on the heat transfer and pressure drop performance of a heat exchanger. Through experimental research, the results showed that the fluctuation of the UA (U is the heat transfer coefficient; A is the heat exchange area) value first increased and then decreased with an increase in the sloshing amplitude. The UA value increased by 12.92% and decreased by 42.03% compared to the static value at 3 and 9°, respectively. The fluctuation in the UA value first decreased and then increased with an increase in the sloshing period. The UA value decreased by 36.66% and increased by 10.82% slowly compared to the static value when the sloshing period was 6 and 20 s, respectively. Based on this, a mathematical model of heat transfer under the condition of pitch sloshing was established.