diff --git a/src/cmd_crate.rs b/src/cmd_crate.rs
index f28e6f4..222e4a1 100644
--- a/src/cmd_crate.rs
+++ b/src/cmd_crate.rs
@@ -1,3 +1,5 @@
+use std::fs;
+use std::collections::HashMap;
 use std::time::Duration;
 use clap::{ArgMatches, SubCommand, App, Arg};
 use crates_io_api::{SyncClient, CrateResponse};
@@ -19,9 +21,65 @@ impl Command for CommandImpl {
             "cargotool (https://hatter.me/)", Duration::from_millis(1000)
         )?;
 
+        let toml_str = match fs::read_to_string("Cargo.toml") {
+            Ok(s) => s, Err(e) => {
+                failure!("Read file Cargo.toml failed: {}", e);
+                return Ok(());
+            },
+        };
+        let mut toml: toml::Value = match toml_str.parse() {
+            Ok(t) => t, Err(e) => {
+                failure!("Parse Cargo.toml failed: {}", e);
+                return Ok(());
+            },
+        };
+
+        let mut exists_dependencies_map: HashMap<String, String> = HashMap::new();
+        if let toml::Value::Table(cargo_map) = &toml {
+            if let Some(toml::Value::Table(dependencies)) = cargo_map.get("dependencies") {
+                for (k, v) in dependencies.iter() {
+                    match v {
+                        toml::Value::String(s) => {
+                            exists_dependencies_map.insert(k.clone(), s.clone());
+                        },
+                        toml::Value::Table(t) => {
+                            if let Some(toml::Value::String(version)) = t.get("version") {
+                                exists_dependencies_map.insert(k.clone(), version.clone());
+                            }
+                        },
+                        _ => (),
+                    }
+                }
+            }
+        }
+
+        let mut is_updated = false;
         if let Some(add_crates) = sub_arg_matches.values_of("add") {
             for c in add_crates {
-                find_create(&crate_io_client, c);
+                if exists_dependencies_map.contains_key(c) {
+                    warning!("Crate: {} exists!", c);
+                } else {
+                    if let Some(crate_response) = find_create(&crate_io_client, c) {
+                        if let toml::Value::Table(cargo_map) = &mut toml {
+                            if let Some(toml::Value::Table(dependencies)) = cargo_map.get_mut("dependencies") {
+                                is_updated = true;
+                                let crate_data = crate_response.crate_data;
+                                dependencies.insert(crate_data.id, toml::Value::String(crate_data.max_version));
+                                success!("Adding crate: {}", c);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        if is_updated {
+            match toml::to_string_pretty(&toml) {
+                Err(e) => failure!("Generate toml failed: {}", e),
+                Ok(t) => match fs::write("Cargo.toml.new", t) {
+                    Err(e) => failure!("Write to file: Carto.toml, failed: {}", e),
+                    Ok(_) => success!("Write to file: Cargo.toml success!"),
+                },
             }
         }