The importance of teachers' language assessment literacy (LAL) is widely acknowledged. However, due to the multi-faceted (Inbar-Lourie, 2013), contextually situated (Fulcher, 2012), all-encompassing (Giraldo & Murcia, 2019) and developing (Xu & Brown, 2016) nature of LAL, there is still lacking a widely received definition or framework of teachers' LAL (Giraldo, 2018; Stabler-Havener, 2018). In the digital age, the impact technology brings to assessment cannot be ignored (Yu & Zhang, 2017). Teachers need to equip themselves with new competencies to face the new challenges involved in digital language assessment (Eyal, 2012; Taylor & Harding, n.d.), which become more prominent under the impact of the Covid-19 pandemic. However, the digital aspect is only implicitly shown in LAL conceptualisations (Kremmel, 2020). The present study investigated China's university English language teachers' LAL. It included two sub-studies, each adopting a sequential explanatory mixed-method design. Study 1 involved a large-scale survey (1045 respondents) with 56 follow-up interviews. A bespoke LAL framework was produced based on the survey data, comprising 12 components with a clear digital language assessment component and classroom-based assessment being the area that teachers consider they should develop the most. The framework also illustrates the specific contextual and personal factors that influence the construct of teachers' LAL. Using the framework as the test blueprint, the Teachers' Language Assessment Literacy Test (TLALT) was developed in Study 2. 742 China's university English teachers took the test; and 39 were interviewed afterwards. The test results showed that teachers had the lowest competences in "digital language assessment" and "measurement theories" and the highest competences in "test design" and "theories and standards of language and language learning". Approaches or factors that facilitate or impede teachers' LAL development were explored and it is found that teachers mainly depended on themselves to cultivate LAL while institutions provided more barriers than facilitators in teachers' LAL development. Teachers' demographic characteristics proved to have very different impacts on teachers' perception of LAL and teachers' LAL levels. Administrative job title and research interest exert influences on teachers' LAL perceptions, while gender, teaching course, teaching cohort, assessment training experience and research interest show a significant impact on teachers' LAL level. Research interest has an impact on both teachers' LAL perception and competence, confirming the importance of research to China's university English teachers and their triple role of instructor, assessor and researcher. This study reveals the severe LAL deficiency problem in China's university English teachers. To support their LAL development, the LAL framework proposed in this project can be used to guide the development of teachers' LAL standards and the design of assessment training programmes. The TLALT can be used to assess or diagnose teachers' LAL, which can facilitate teacher training or self-learning in LAL. The landscape of teachers' LAL levels can be used to guide assessment-related policies within or beyond institutions, which should also take into account the demographic factors that were found to exert influences on teachers' LAL. This study presents a practical approach that can be replicated in other contexts to produce a bespoke LAL framework for a specific stakeholder group.