With　rapid　development　of　enabling　technologies　such　as　Internet　of　Things,　robotics,　and　big　data,　the　fourth　industrial　revolution　known　as　＂Industry　4.0＂　(I4.0)　has　become　a　great　opportunity　for　productivity　innovation　around　the　world.　Industrial　Internet　of　Things　(IIoT),　as　a　typical　implication　of　Cyber-Physical　Systems　(CPS)　in　I4.0　era,　has　attracted　significant　attention.　It　aims　at　optimizing　resources　and　improving　production　efficiency　for　manufacturing　industry　through　deep　interconnection　of　physical　equipment,　wide　collection　of　multi-dimensional　data,　intelligent　awareness　of　environment　and　automatic　control.　Blockchain　is　a　kind　of　distributed　ledger　technology　and　has　features　including　decentralization,　anti-tamper,　transparency,　anonymity,　and　contract-autonomy.　These　features　are　helpful　to　improve　the　services　and　promote　the　development　of　IIoT.　In　this　paper,　we　provide　a　comprehensive　survey　on　the　literatures　applying　blockchain　technology　into　IIoT.　We　firstly　introduce　the　related　works　and　background　knowledge.　And　then,　the　motivations　and　benefits　for　applying　blockchain　into　IIoT　are　discussed　in　detail.　Furthermore,　based　on　the　layered　architecture　of　blockchain　we　summarized　in　the　previous　work,　we　outline　the　research　framework　of　blockchain　in　IIoT.　Meanwhile,　the　related　application　research　is　presented　from　the　perspectives　of　devices　security,　data　collection　and　sharing,　and　industrial　application.　Moreover,　we　explore　the　technical　requirements　of　blockchain　platforms　in　IIoT　applications.　Finally,　some　challenges　and　future　directions　on　blockchain　in　IIoT,　as　well　as　broader　perspectives,　are　concluded　for　further　study.