Prehospital fluid resuscitation with crystalloids in patients following trauma remain controversial. This study aimed to investigate the association between prehospital fluid resuscitation and outcomes of trauma patients in Asia. We conducted a retrospective cohort study of trauma patients between 2016 and 2018 using data from the Pan-Asia Trauma Outcomes Study (PATOS) database. Prehospital fluid resuscitation was defined as any administration of intravenous crystalloid fluid on the ambulance before arrival to hospitals. The outcomes were in-hospital mortality and poor functional outcomes, defined as Modified Rankin Scale ≥ 4. Propensity score matching (PSM) was used to equalize potential prognostic factors in both groups. This study included 31,735 patients from six countries in Asia, and 4318 (13.6%) patients had ever received prehospital fluid resuscitation. The patients receiving prehospital fluid resuscitation had a higher risk of in-hospital mortality, with an adjusted odds ratio (aOR) of 2.02, 95% confidence interval (CI) 1.32–3.10, p = 0.001 in PSM analysis. Prehospital fluid resuscitation was also associated with poor functional outcomes, with an OR 1.73, 95% CI: 1.48–2.03, p < 0.001 in PSM analysis. Prehospital fluid resuscitation in patients with major trauma (injury severity score ≥ 16) presented a higher risk of poor functional outcomes (aOR = 2.65, 95% CI: 1.89–3.73 in PSM analysis, pinteraction = 0.006) via subgroup analysis. Prehospital fluid resuscitation of trauma patients is associated with higher in-hospital mortality and poor functional outcomes in the subgroup in countries studied.