Phospholipid bilayer nanodiscs， a newly developed model membrane system， provides "native-like" membrane environment for membrane protein studies. Nanodiscs assembled by membrane scaffold protein and phospholipid bilayer， with defined sizes that can be accurately regulated by changing the amino acid residues of the MSP construct. Herein we described the expression and purification of ΔMSP， a deletion mutant of the membrane scaffold protein. Smaller nanodiscs with mixed lipids were assembled， and the observed (31)P NMR spectra showed identical chemical shifts to those of nanodiscs with pure POPC and POPE lipids， indicating they share similar chemical environments. The success of incorporation STIM1-TM into nanodiscs indicated the application of this smaller nanodisc system can be used to membrane protein studies by solution NMR.