In hard-rock strata, the conical picks of cantilever roadheaders suffer from severe wear and require frequent replacement, yet quantitative criteria for determining cutter replacement timing are currently lacking. To address the deficiencies in categorized control for conical pick replacement decision-making, 402 cutter samples collected from the A-line of the LTTG water conveyance tunnel branch line were taken as the research object, and the statistical characteristics of wear and failure of conical picks in the hard-rock excavation section were systematically investigated. Based on digital image processing technology, a strategy for extracting and quantitatively characterizing cutter geometric morphology was introduced, and a comprehensive evaluation method for conical pick replacement decision-making integrating quantitative indices and qualitative criteria was further proposed. The results show that the main failure modes of conical picks in gneiss formations are uniform wear (34.1%), carbide tip failure (27.4%), overall wear (23.1%), and eccentric wear (15.4%). The failure determination of conical picks should not only establish criteria from the two dimensions of mass loss and geometric morphology deviation, but also incorporate the health condition of the carbide tip to establish qualitative criteria for sudden cutter failure. On this basis, wear rate (≥13.0%), asymmetry coefficient (≥2.7%), and carbide tip failure were adopted as the core criteria for cutter replacement decision-making, and a comprehensive evaluation system for the failure state of conical picks was constructed. This method can provide a reference for the state identification and replacement decision-making of conical picks in hard-rock strata.