Abrasive jet micromachining (AJM) is a promising machining technique for the cost effective fabrication of micro devices from brittle and hard materials. The machining process is based on the erosion of brittle substrate by an abrasive-laden air jet. For the machining process to be more efficient and better predictable, modeling and simulation of AJM process is necessary. This study aims to develop a new model for AJM process based on a fundamental erosion model of solid particle impact for brittle materials, and a recently developed model for the particle velocity in micro-abrasive jet. Preliminary modeling approaches and experimental results are presented and discussed.