Lateral-force　microscopy　is　a　powerful　tool　to　study　the　frictional　properties　of　two-dimensional　materials.　However,　few　works　distinctly　reveal　the　correlation　between　the　tip　radius　with　the　tip-sample　distance　and　the　frictional　properties　of　the　two-dimensional　(2D)　materials.　We　performed　molecular-dynamics　simulations　to　study　the　atomic-scale　friction　of　a　typical　two-dimensional　single-layer　molybdenum　disulfide　(SLMoS2).　The　effects　of　tip　radius　and　tip-sample　distance　on　the　frictional　properties　were　analyzed　and　discussed.　The　frictional　force-sliding-distance　curves　show　typical　stick-slip　behaviors,　and　the　periodicity　can　be　used　to　characterize　the　lattice　constants　of　SLMoS2.　Sub-nanoscale　stick-slip　movements　occur　in　one-lattice　sliding　periods　along　with　only　the　armchair　(AC)　direction　and　only　when　the　tip　radius　is　smaller　than　3　angstrom　with　1.47　angstrom　tip-sample　distance.　At　the　same　tip-sample　distance,　a　smaller　tip　can　provide　a　more　detailed　characterization　and　higher-precision　frictional　properties　of　SLMoS2.　A　larger　tip　is　capable　of　providing　comparative　frictional　properties　of　SLMoS2　at　a　proper　vertical　tip-sample　distance,　compared　with　the　small　tip.