China has drawn up ambitious plans in nuclear power development. After the Fukushima crisis, the HK public has expressed serious concerns about the nuclear power plants in the cross-border Guangdong region. We conducted a randomized survey of 1032 HK respondents to identify the key factors that predict HK Government’s trustworthiness (GT), with regard to nuclear safety emergency governance in a cross-border context. Our result shows that the perceived benefit of nuclear power is positively associated with GT, while risk perception about nuclear power technologies, expected engagement in emergency planning, and average monthly income are negatively associated with GT. We also find that knowledge about nuclear technology and safety has no effect on GT. This contradicts the common view that educating the public about nuclear safety and technology will increase public trust. Further, we find that HK respondents prefer engaging with local experts than international/Guangdong authorities. To build trust in NSEG, HK Government should direct attentions towards improving public understanding on the significance and contribution of nuclear power in overall electricity generation in HK, reducing public fears of nuclear power technologies, and ensuring appropriate level of engagement with HK stakeholders. Our proposed methodology can be transferrable to other domains and countries.