Butanol/diesel blend is considered as a very promising alternative fuel with agreeable combustion and emission performance in engines. This paper intends to further investigate its autoignition characteristics with the combination of a heated rapid compression machine (RCM) and a heated Shock Tube (ST) to acquire a wide temperature region view. The ignition delay times (IDTs) of mixtures of 20% blending (by vol.) of n-butanol to China Stage-VI diesel, referred to as N20, were studied under the pressures of 6/10/15 bar, the equivalence ratios of 0.5-2.0, and a broad temperature range of 670-1300 K. Typical two-stage ignition and NTC behavior of the fuel were identified, and the IDT dependences on the compressed pressure, fuel/oxygen fraction, and the blending ratio were explained thoroughly and quantitively with correlation formulas. Furthermore, this paper expands the study to the effects of butanol structures. Autoignition characteristics of mixtures of 20% blending (by Vol.) of each of the four butanol isomers with neat diesel were investigated experimentally and numerically. The CRECK model was validated against the experimental results and critical reactions controlling fuel ignition were identified for further optimization. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.