Quantitative assessment of articular cartilage is important for the early diagnosis of osteoarthritis, intra-operation joint tissue evaluation and judgment of repaired cartilage quality. This technique is also applicable to the cartilage if arthroscopic instrument embedding this technique can be developed. In this study, an arthroscopic water-jet ultrasound indentation probe was developed with the help of a small profile intra-articular ultrasound imaging (IAUS) catheter for the intra-articular measurement of cartilage condition. The probe can provide measurement of morphological, acoustical and mechanical properties of articular cartilage. Preliminary tests were conducted on 10 intact porcine knees with the guide of arthroscopy for the evaluation of cartilage degeneration, which was induced by trypsin digestion. Results showed the cartilage stiffness decreased significantly after the digestion (p <; 0.001) with the measurement conducted by the developed probe. In summary, an arthroscopic ultrasound probe has been successfully developed and its utility in detecting the cartilage degeneration was demonstrated in this study. Future work includes the improvement of the probe design and studies on measurement of animal or human samples in vivo.