The invention provides a guardrail device of a bridge. The guardrail device comprises a bridge base body (1) and a plurality of guardrail units (2) installed on the bridge base body (1). Each guardrail unit (2) comprises two fixed sleeve stand columns (4) which are fixed to the bridge base body (1) in a bilateral symmetry mode, an upper cross beam (21) and a lower cross beam (22), wherein the upper cross beam (21) and the lower cross beam (22) stretch across and extend across the space between the two fixed sleeve stand columns (4); the upper cross beam (21) and the lower cross beam (22) are each provided with a circuit assembly and are fixedly connected through vertical railings (23). Each fixed sleeve stand column (4) is provided with a bolt hole in thread fit with a vertical stud (43). The upper end of each vertical stud (43) stretches into the upper cross beam (21) and fixedly and axially connected with the upper cross beam (21) through an upper thrust bearing (431) and a lower thrust bearing (432).