An interval-parameter integer non-linear programming (IPINP) model is developed for the assessment of filter allocation and replacement strategies in a hydraulic contamination control system under uncertainty. The IPINP can handle uncertainties expressed as interval values that exist in the left- and right-hand sides of constraints as well as in the objective function. A piecewise linearization approach is proposed to solve the IPINP model, which has advantages in identifying global optimum and is associated with low computational efforts for an uncertain non-linear programme. The developed method has been applied to a case of planning filter allocation and replacement strategies under uncertainty for a fluid power system (FPS) with a single circuit. Three different contaminant ingression/generation rates are examined based on several filter-installation scenarios. The combination of low-costing suction and return filters exhibits excellent contaminant resistibility along with the optimum replacement periods of filter elements and operation costs under the low and medium contaminant ingression/generation level. The solutions can be used for generating a range of decision alternatives and thus help the decision-makers to identify desired filter allocation and replacement plan with a minimized operation cost and a minimized system-failure risk for FPS.