The emergence of full-screen mobile phones and tablet PCs has motivated ERP vendors to adopt a mobile strategy in order to extend their products' features. Several researchers have pointed out that ERP systems' UIs suffer from poor usability, due to their complex, rigid and bloated UIs, since these systems have to process and integrate a large amount of data. Therefore, accessing ERP systems via mobile devices like fullscreen phones or tablet PCs suffers from UIs usability challenges. Currently, mobile ERP is a young topic in research and practice, there are only few academic papers available about mobile ERP. Particularly, there is a knowledge gap in addressing the usability issues when designing the mobile ERP's UIs and determining a suitable usability evaluation method and criteria which are specific to mobile ERP. This paper aims at narrowing that gap by proposing a set of usability heuristics and a UI design checklist dedicated to evaluate mobile ERP's UIs which can be used by mobile ERP developers.