Literacy,especially mother tongue literacy,plays a significant role in our daily life.Khmer language is a Cambodian mother tongue and official language used by 90 percent of the whole population.It is also a Cambodian identity and used as a medium of instruction from preschool to high school including some universities.However,illiteracy is not only seen as a major concern for Cambodian society but also worldwide issue.Yet Cambodia confronts this issue since the early grade.The Khmer literacy performance is low for the primary grade student.For example,as mentioned by USAID in 2015,one second of grade-one students could not recognize a single letter while half of the grade-two students were unable to read any familiar words.In addition,Brown wrote in 2018,twenty-five percent of grade three students are unable to write a single word in the dictation test.Scientifically,there is a strong support that early intervention in preschool,especially early literacy contributes to later success in academic learning.In this light,the Mo EYS from 2011 to 2017 shows that the preschool enrolment rate is positively increased year by year from 1555 students in academic year 2000/2001 to 190148 students in academic year 2016/2017.However,Ministry of Education,Youth and Sport found some challenges in preschool education such as lack of teaching materials,lack of financial and emotional support,and ineffective curriculum that does not meet the standard.Therefore,this study is conducted to explore the teacher challenges in teaching Khmer literacy to rural preschools.The objective of this study is to identify the teaching approaches/methods of Khmer literacy,to explain the reason why they chose to teach children in that way,to explore what challenges faced by those rural teachers and how do they solve those problems.A convenient sampling is used to select six teachers from three public schools located in Rattanak Mondol district,Battam Bang province,Cambodia.Qualitative method is adopted while observation,informal interaction and semi-structured interviews are employed to gather the data.To analyze the data,grounded-theory is used.The finding of the study revealed that the teachers used explicit instruction approach and playbased learning to teach children Khmer literacy.Corporal punishment is used by the teachers.The teachers employed those teaching approaches according to the curriculum design,their belief,knowledge,and experience constructed by resources provided by Mo EYS,school factor,and their own practice.The major challenges found in this study such as lack of teaching and learning materials,the inconvenient classroom learning environment,the shortage of preschool teachers and classrooms,larger classroom size,the curriculum(it does not meet the teacher and parent expectation,irregular page,obscure teaching instruction and strategies,limited hour for teaching literacy),misbehavior and undisciplined student,lack of parental involvement,difficulty in teaching new songs,lack of pedagogical content knowledge,lack of financial support,student diversity,and insufficient of professional development training and resource.