Recently, various refractory high entropy superalloys, which have unique microstructure containing cuboidal nano-precipitates in BCC high entropy alloy (HEA), reported. They exhibited superior mechanical properties at both ambient and high temperature. However, there are many unsolved issues to attract even greater attention such as precipitation control of unwanted compounds, optimal phase selection between ordered and disordered BCC, and optimization of mechanical properties etc. In the present study, we propose how to tailor the microstructure of refractory high entropy superalloy through a bulk combinatorial approach in Ti-Hf-Nb-Al quaternary HEAs. Microstructural evolution for the non-equiatomic HEA compositions obtained by a bulk combinatorial approach were systematically investigated by considering phase transformation mechanism as well as phase equilibria. This result could provide an effective guideline for tailoring microstructure of HEAs with ordered and disordered BCC phases, and developing a promising high entropy superalloy with customized microstructure for ultra-high temperature structural application.