Abstract: Digital technology has dual features. One is the basic features of editability, addressability, communicability and generativity. The other is the generality, evolvability, uncertainty and externality derived from the interaction with manufacturing entities and the integration process. The basic features of digital technology determine that it plays a unique role in the digital transformation of the manufacturing industry, resulting in transformation effects, including digital effect, openness effect, agility effect and value-added effect. For the digital transformation of SMEs, the derivative features of digital technology also restrict the transformation effects to a certain extent, thus constituting transformation barriers: the transformation conditions behind the generality affect the digital effect; the transformation costs caused by evolvability and uncertainty weaken the value-added effect; data security and other transformational constraints spawned by externality restrict the openness and agility effects. In the practice of manufacturing SMEs digital transformation, various practical problems inherent in SMEs entangle with transformation thresholds, transformation costs and transformation constraints, which constitutes more complex practice problems. Based on the above discussion, this paper proposed that we should adopt following countermeasures including establishing a digital talents training system to narrow the transformation thresholds gap, improving the digital product and servicing supply market to reduce transformation costs, introducing support policies based on industry differences to cope with negative effects of other transformations constraints, to overcome transformation barriers and promote the digital transformation of manufacturing SMEs.