Heavy　vehicle　steering　testboard　has　a　key　role　to　play　in　the　fundamental　research　of　heavy　vehicle　steering　performance,　and　pressure　control　of　electro-hydraulic　servo　loading　system　is　the　precondition　and　foundation　for　achieving　accurate　dynamic　loading　of　heavy　vehicle　steering　testboard.　Commonly　used　proportional-integral-differential　control　easily　fails　to　track　target　pressure　signal　with　high　amplitude　and　frequency,　while　integral　sliding　mode　control　is　capable　of　realizing　pressure　tracking　with　high　accuracy　in　engineering　for　its　strong　robustness　and　simplicity.　A　nonlinear　mathematical　model　of　electro-hydraulic　servo　loading　system　is　established,　including　the　nonlinear　characteristics　of　valve-controlled　cylinder　system　and　tire　elastic　force,　and　an　integral　sliding　mode　controller　is　also　designed　in　this　paper.　For　further　comparison　and　analyses,　based　on　particle　swarm　optimization　and　integral　of　the　time　absolute　error　criterion,　a　proportional-integral-differential　self-tuning　controller　of　electro-hydraulic　servo　loading　system　is　proposed　as　well,　and　the　corresponding　optimal　proportional-integral-differential　control　gains　are　obtained.　Both　numerical　simulation　and　experiment　results　confirm　that,　compared　with　proportional-integral-differential　self-tuning　control,　integral　sliding　mode　control　can　effectively　suppress　the　disturbance　of　external　loads　and　reach　a　better　pressure　tracking　performance.