Understanding　the　mechanical　and　deformation　failure　behaviors　of　heated　flawed　granite　under　true　triaxial　stresses　is　of　great　significance　for　evaluating　the　wellbore　stability　in　developing　hot　dry　rock　resources.　In　this　study,　true　triaxial　experiments　are　conducted　on　flawed　granite　specimens　of　a　varying　flaw　overlapping　length　lfo　with　and　without　high　temperature　(HT)　treatment,　with　the　emphases　on　the　crack　development　under　true　triaxial　stresses　and　its　correlations　with　the　strength,　plastic　anisotropy　and　failure　forecast.　Investigations　demonstrate　that　HT,　σ2　(intermediate　principal　stress)　and　lfo,　significantly　affect　the　mechanical　properties　of　flawed　granite.　Due　to　strong　3D　confinement,　the　loop　crack,　the　secondary　transverse　crack　and　the　far-field　crack　are　frequently　induced　in　flawed　granite,　unlike　experiments　of　uniaxial,　biaxial　and　conventional　triaxial　compression.　When　increasing　lfo,　the　rock　bridge　undergoes　the　stress　amplification　which　tendentiously　drives　the　internal　crack　coalescence　and　typically　causes　a　reduced　strength.　The　PSIRs　(Plastic　Strain　Increments　Ratios)　analysis,　first　extended　to　the　true-triaxial　experimental　data,　reveals　that　the　3D　stress-induced　extensional/shear　fracturing　from　the　flaw　tips　in　σ2-direction　is　the　mechanism　of　the　plastic　anisotropy　generated.　Besides,　an　attempt　to　anticipate　the　failure　time　in　the　framework　of　the　time‐reversed　Omori＇s　law　suggests　a　poor　predictability　by　using　the　acoustic　emission　but　a　higher-quality　forecast　(being　more　precise　and　less　biased)　by　using　the　dissipated　energy.　©　2024　Elsevier　Ltd